High-performance non-contact support platforms

ABSTRACT

A non-contact support platform for supporting without contact a stationary or traveling object by air-cushion induced forces, the platform comprising at least one of two substantially opposite support surfaces, each support surface comprising at least one of a plurality of basic cells each having at least one of a plurality of pressure outlets and at least one of a plurality of air-evacuation channels at least one of a plurality of outlets, and one of a plurality of air-evacuation channels, each of the pressure outlets fluidically connected through a pressure flow restrictor to a high-pressure reservoir, the pressure outlets providing pressurized air for generating pressure induced forces, maintaining an air-cushion between the object and the support surface, the pressure flow restrictor characteristically exhibiting fluidic return spring behavior; each of said at least one of a plurality of air-evacuation channels having an inlet and outlet, the inlet kept at an ambient pressure or lower, under vacuum condition, for locally discharging mass flow, thus obtaining uniform support and local nature response.

FIELD OF THE INVENTION

The present invention relates to non-contact supporting and conveyingplatforms and handling tools. More particularly, it relates platformsfor supporting and conveying flat objects, such as silicon-wafers orFlat Panel Displays (FPD), (but not necessarily limited to thin or flatobjects), that make beneficial use of various types of air-cushions thatare based on same generic fluidic element, hereinafter referred to asthe “fluidic return spring”, to provide high performance non-contactplatforms and handling tools.

BACKGROUND OF THE INVENTION

In resent years, much attention has been given to the option of usingnon-contact equipment for supporting, gripping or conveying products inmanufacturing processes. In particular, such non-contact equipment has aunique appeal for high-tech industry where the production is highlysusceptible to direct contact. It is especially important in thesemiconductors industry, in the manufacturing phase of silicon wafers,Flat Panel Displays (FPD) and Printed Circle Boards (PCB), as well ascomputer's hard-discs, compact discs (CD), DVD, liquid crystal display(LCD) and similar products. Non-contact equipment can beneficially beapplied also in the manufacturing phase of optical equipment and in theprinting world, mainly in wide format printing when apart from papers,printing is performed on various types of “hard” materials.

By using non-contact equipment, many problems that are associated withthe manufacturing phase may be solved and directly enhance theproduction yield. Without derogating the generality, some of theadvantages in using non-contact systems includes, inter alia:

-   (a) Eliminating or greatly reducing mechanical damages—including,    for example, impact, press, but, most importantly, any friction that    may be involved. Friction is inherently eliminated in non-contact    systems.-   (b) Eliminating or greatly reducing in-contact contamination—a very    important feature for semiconductors production lines of silicon    wafers and FPDs.-   (c) Eliminating or greatly reducing electrostatic discharge (ESD).    Critical ESD problems may be founds in the semiconductors production    lines of FPD and silicon wafers.-   (d) Eliminating or greatly reducing in-contact local deformation of    objects due to particles that are trapped on the contact surface,    between the product and the in-contact equipment. Such problems may    occur when a wafer is gripped by an electrostatic or vacuum chuck    during a sequential lithography process in the semiconductors    industry.-   (e) Non-flatness of local nature, found in in-contact equipment, is    inherently averaged when using non-contact equipment.

Additional benefits of using non-contact equipments can be obtained:

-   (f) Conveying of products by moving only the product thus avoiding    the need to move also the holding-table that may be of much heavier    weight than the product itself, a situation that is typically found    in the FPD market and semiconductors industry as well as in the    printing world.-   (g) Conveying the product accurately where accuracy can be provided    only at a small distinct area or along a narrow line where the    process is executed continuously of step-by-step during the travel    of the product. It is relevant in steppers that are widely in use    the semiconductors industry with planar (X,Y) wafer motion is    applied, when rotating the wafer during inspection, or when linear    motion in one direction is applied in the manufacturing line of FPD.-   (h) To flatten with no contact, by pure moments enforcing, objects    that are not flat, in order to provide accurate gripping. It is    important for PCB & FPD makers as well as in the semiconductors    industry where both regular or thin wafers have to be flatten prior    to many processes. It is also important in the printing world when    media other than paper is used, including direct digital writing on    different media, and printing-plate for off-set printing and press.    In most of these examples, optics or optical imaging is involved    where the focal distance must be very accurate.

Commonly, such systems comprise a flat platform having one or moreactive-surfaces. Each of the active-surfaces, that are in most casesflat, is equipped with a plurality of pressure ports for providingpressurized air aimed at generating an air-cushion. An air-cushion isdeveloped when a surface, that is flat in most cases, is placed over theactive surface at a close range. Air-cushion support can be preloaded bythe object weight, by pressure dual-side configuration or preloaded byvacuum. In case of light weight, as in many cases of the productsmentioned above, high performance air-cushion support, in many cases,adopts the pressure or vacuum preloading approaches.

Currently used non-contact supporting and conveying systems that arebased on air-cushions offer limited performance in many aspects. Theselimited performance aspects are mainly related to the relatively highmass flow or energy consumption associated with these systems, and tothe accuracy performance that is directly related to the aero-mechanicstiffness of the air-cushion. The non-contact supporting and conveyingequipment of the present invention that implements various types ofair-cushions, employing a plurality of flow-restrictors that arefunctioning as a “fluidic return springs”, and provide effectivehigh-performance air-cushion support at much lower mass flow consumptionwith respect to conventional non-contact equipment. In particular, whenusing non-contact platforms where the active-area is much larger thanthe confronting surface of the supported object and most of theplatform's active area is not cover, the use of flow restrictorsprovides an efficient and cost-effective non-contact platform in termsof mass flow consumption. With respect to the present invention, a flowrestrictor is individually installed in each conduit of the pressureports of the non-contact platform active-area. By active area is meant,throughout the present specification the area of the support surfacewhere injecting ports are distributed. It is preferred, for the purposesof the present invention, to use self-adaptive segmented orifice (SASO)nozzles as the preferred flow-restrictors, so as to effectively producethe fluidic return spring effect.

PCT/IL00/00500, published as WO 01/14752, entitled APPARATUS FORINDUCING FORCES BY FLUID INJECTION, described the SASO nozzle and itsuses in non-contact supporting systems. It is a purpose of the presentinvention to provide, in preferred embodiment of the present invention,a novel high-performance non-contact supporting and conveying platformsbased on air-cushion technology that employs the SASO nozzle as afluidic return spring and that is capable of limiting the flow of airthrough these nozzles.

The self adaptive segmented orifice (SASO) flow control devicecomprising a fluid conduit, having an inlet and outlet, provided withtwo opposite sets of fins mounted on the inside of the conduit, each twofins of same set and a portion of the conduit internal wall between themdefining a cavity and the fin of the opposite set positioned oppositesaid cavity, so that when fluid flows through the conduit substantiallystationary vortices are formed in the cavities said vortex existing atleast temporarily during the flow thus forming an aerodynamic blockageallowing a central core-flow between the vortices and the tips of theopposite set of fins and suppressing the flow in a one-dimensionalmanner, thus limiting the mass flow rate and maintaining a substantialpressure drop within the conduit. It exhibits the followingcharacteristics of the SASO nozzle:

-   (a) A fluidic return spring effect is established when pressurized    air is supplied at the inlet to the SASO-nozzle and the outlet is    partially blocked by an objects but not closed completely, allowing    air flow out of the outlet, in such a way that a potion of the    supply pressure is dropped inside each of the SASO-nozzles and the    remaining pressure is introduced to the air cushion, that is    developed in the narrow gap between the “active surface” of that    platform having the SASO-nozzle outlets and the surface of the    object, thus force is applied on the object to elevate it. The    pressure introduced to the air cushion is increased as the gap is    decreased and is decreased as the gap is increased. If, for example,    the object is supported by an air-cushion, this pressure establishes    a force that balances the object's weight. The object is floating    over the non-contact platform active-surface at a self-adaptive    manner where, with respect to this example, the air-cushion gap is    self-defined to such a levitation distance that the total forces    up-wise that act on the floating object are equal to the gravity    force. The fluidic return spring behavior is obtained when trying to    change that balanced situation: when trying to close the gap, the    pressure at the air-cushion is increased and pushes the object up to    the balanced air-cushion gap, and when trying to open the gap, the    pressure at the air-cushion is decreased and the gravity force pulls    the object down to the balanced air-cushion gap. This simple example    is given to clarify the functionality of the fluidic return spring,    but in general it can be applied in various ways as will be    discussed hereinafter.-   (b) An aerodynamic blockage mechanism is obtained when the    SASO-nozzle outlet is not closed. In fact, a SASO-nozzle has    laterally large physical scales to prevent mechanical blockage by    contaminating particles, and when it is totally covered (as the flow    stops, the aerodynamic blockage dissipates), it introduces pressure    or vacuum at the platform active surface with no losses. But, when    the SASO-nozzle outlet is not closed and a through-flow exists, it    has a dynamic behavior of a small orifice that is controlled by the    aerodynamic blockage mechanism. This behavior is significantly    important as the mass flow rate is dramatically reduced when the    non-contact platform supporting or conveying a smaller in size    object and a large portion of it's active surface is not covered.

The SASO-nozzle is a flow-control device that has a self-adaptivenature, based purely on aero-dynamic mechanism, with no-moving parts orany means of controls. As it has laterally large physical scales, it isnot sensitive to contamination blockage. When using a plurality ofSASO-nozzles to feed a well functioning air-cushion, it has a localbehavior that provides homogeneous air-cushion.

BRIEF DESCRIPTION OF THE INVENTION

There is therefore provided, in accordance with a preferred embodimentof the present invention, a non-contact support platform for supportingwithout contact a stationary or traveling object by air-cushion inducedforces, the platform comprising:

-   at least one of two substantially opposite support surfaces, each    support surface comprising at least one of a plurality of basic    cells having at least one of a plurality of pressure outlets and at    least one of a plurality of air-evacuation channels at least one of    a plurality of outlets, and one of a plurality of air-evacuation    channels, each of the pressure outlets fluidically connected through    a pressure flow restrictor to a high-pressure reservoir, the    pressure outlets providing pressurized air for generating pressure    induced forces, maintaining an air-cushion between the object and    the support surface, the pressure flow restrictor characteristically    exhibiting fluidic return spring behavior; each of said at least one    of a plurality of air-evacuation channels having an inlet and    outlet, the inlet kept at an ambient pressure or lower, under vacuum    condition, for locally discharging mass flow, thus obtaining uniform    support and local nature response.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the pressure flow restrictor comprises a conduit, having aninlet and outlet, provided with two opposite sets of fins mounted on theinside of the conduit, each two fins of same set and a portion of theconduit internal wall between them defining a cavity and the fin of theopposite set positioned opposite said cavity, so that when fluid flowsthrough the conduit substantially stationary vortices are formed in thecavities said vortex existing at least temporarily during the flow thusforming an aerodynamic blockage allowing a central core-flow between thevortices and the tips of the opposite set of fins and suppressing theflow in a one-dimensional manner, thus limiting mass flow rate andmaintaining a substantial pressure drop within the conduit.

Furthermore, in accordance with a preferred embodiment of the presentinvention, said at least one of a plurality of air-evacuation channelsincludes an evacuation flow restrictor.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the evacuation flow restrictor comprises a conduit, having aninlet and outlet, provided with two opposite sets of fins mounted on theinside of the conduit, each two fins of same set and a portion of theconduit internal wall between them defining a cavity and the fin of theopposite set positioned opposite said cavity, so that when fluid flowsthrough the conduit substantially stationary vortices are formed in thecavities said vortex existing at least temporarily during the flow thusforming an aerodynamic blockage allowing a central core-flow between thevortices and the tips of the opposite set of fins and suppressing theflow in a one-dimensional manner, thus limiting mass flow rate andmaintaining a substantial pressure drop within the conduit.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the evacuation channels are fluidically connected to a vacuumreservoir.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the vacuum flow restrictor has significantly loweraerodynamic resistance than the pressure flow restrictor.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the vacuum flow restrictors are designed so as to lower thevacuum level to a value in the range of 70%-90% of the vacuum of thevacuum reservoir.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the absolute value of pressure supply to the platform islarger by a factor of 1.2.-3 with respect to the absolute value ofvacuum supply to the platform.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the support surface comprises at least one of a plurality ofplanar surfaces.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the support surface is flat.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the support surface is provided with grooves.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the support surface is cylindrically shaped.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the support surface is substantially rectangular.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the support surface is substantially circular.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the support surface is constructed from plates in a layeredformation.

Furthermore, in accordance with a preferred embodiment of the presentinvention, at least one of the plates contains a plurality of voidsconstructing the flow restrictors and inter-layer passages for theair-evacuation channels and for pressure or vacuum supply.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the pressure reservoir is in the form of an Integral manifoldwithin the layered-formation.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the evacuation channels are fluidically connected to a vacuumreservoir and the vacuum reservoir is in the form of an Integralmanifold within the layered-formation, constituting a double-manifoldstructure.

Furthermore, in accordance with a preferred embodiment of the presentinvention, said at least one of a plurality of basic cells is providedin a repeated arrangement in order to provide local balance.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the basic cell is provided in a one-dimensional repeatedarrangement.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the basic cell is provided in a two-dimensional repeatedarrangement.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the pressure flow restrictors are designed so as to reducethe pressure supplied by the pressure reservoir to a value in the rangeof 30%-70% of the pressure of the pressure reservoir, to be introducedthrough the pressure outlets to the air-cushion.

Furthermore, in accordance with a preferred embodiment of the presentinvention, at least one of a plurality of through-openings is providedin the support surface, for allowing access to the object for handlingor processing.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the support surface is segmented into several segments,separated by spaces.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the evacuation channels are fluidically connected to a vacuumreservoir, and wherein pressure level in the pressure reservoir orvacuum reservoir is regulated to adjust globally levitation gap of theobject over the support surface.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the evacuation channels are fluidically connected to a vacuumreservoir, and wherein pressure level in the pressure reservoir orvacuum reservoir is regulated in at least one selected separated zone ofthe pressure reservoir or vacuum reservoir, in order to locally adjust tlevitation gap of the object over the support surface.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the evacuation channels are fluidically connected to a vacuumreservoir and wherein along a line of selected separated zones of thepressure reservoir the pressure is individually regulated, in order toflatten the object over the support surface along that line.

Furthermore, in accordance with a preferred embodiment of the presentinvention, along the line selected separated zones parallelism ismaintained with respect to an independent reference.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the selected separated zones are located at edges of thesupport surface to suppress edge effects.

Furthermore, in accordance with a preferred embodiment of the presentinvention, resolution of basic cells at edges of the support surface ishigher with respect to inner zones of the support surface, in order tominimize degrading edge effects of the air-cushion.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the basic cell comprises at least one of a plurality ofevacuation grooves, serving as an air-evacuation channel.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the basic cell comprises at least one of a plurality ofevacuation vents, serving as an air-evacuation channel.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the basic cell comprises at least one of a plurality ofevacuation vents, serving as an air-evacuation channel.

Furthermore, in accordance with a preferred embodiment of the presentinvention, pressure outlets and evacuation channels are arrangedlinearly, pressure outlets aligned in lines and evacuation channelsaligned in lines.

Furthermore, in accordance with a preferred embodiment of the presentinvention, said at least one of two substantially opposing supportsurfaces is oriented so that the object is to be supported below it.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the platform is adapted to be supported or conveyed over theobject, which is stationary.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the object is a carriage and the support surface is anelongated track.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the track is provided with rails on opposing sides of thetrack to limit the motion of the object to a predetermined path over thetrack.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the rails comprise each a platform as claimed in claim 1, foreliminating or greatly reducing friction forces.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the object is a flat track and the support surface isincorporated in a carriage.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the track is provided with rails on opposing sides of thetrack to limit the motion of the carriage to a predetermined path overthe track.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the ratio between the number of pressure outlets andevacuation channels is in the range of 3-16.

Furthermore, in accordance with a preferred embodiment of the presentinvention, gripping means are provided to be coupled to the object forholding or moving the object over the support surface.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the gripping means comprise a gripper unit, which itself issupported with no contact by the support surface.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the gripping means comprise a gripper unit, which itself issupported with no contact by the support surface.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the gripping means is coupled to the object and used toconvey it over the support surface sideways.

Furthermore, in accordance with a preferred embodiment of the presentinvention, gripping means is coupled to the object and used to convey itover the support surface in a linear motion.

Furthermore, in accordance with a preferred embodiment of the presentinvention, gripping means is coupled to the object and used to convey itover the support surface in a rotational motion.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the gripping means is coupled to the support surface and thesupport surface is transportable.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the platform is vertically oriented.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the air-evacuation channels allow air to be passivelydischarged into ambient atmosphere.

Furthermore, in accordance with a preferred embodiment of the presentinvention, more flow restrictors are provided for each basic cell inorder to support a heavier object and vice versa.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the evacuation channels are placed closer to pressure outletsfor supporting a very light object.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the higher the supply pressure is provided to the pressurereservoir the smaller the risk of contact between the object and thesupport surface.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the platform is designed to support an object whichsubstantially covers the support surface, wherein the each of theair-evacuation channels is fluidically connected to a vacuum reservoir,thus generating vacuum-induced forces on the object, facilitatingunilateral gripping of the object without contact by both the pressureinduced forces and the vacuum induced forces, which act in oppositedirections, where aerodynamic stiffness of the air-cushion is augmentedby vacuum-preloading.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the platform is designed to support an object substantiallyis smaller than the support surface, wherein the each of theair-evacuation channels is fluidically connected to a vacuum reservoirthrough a flow restrictor, thus generating vacuum-induced forces on theobject, facilitating unilateral gripping of the object without contactby both the pressure induced forces and the vacuum induced forces, whichact in opposite directions, where aerodynamic stiffness of theair-cushion is augmented by vacuum-preloading.

Furthermore, in accordance with a preferred embodiment of the presentinvention, said at least one of two substantially opposite supportsurfaces comprise only one support surface, and opposite it a passivesurface is provided so that the object may be pressed against thepassive surface without contact by aerodynamically induced forcesgenerated by the support surface.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the passive surface is adapted to be laterally moved.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the passive surface is a rotatable cylinder, that can be usedas a driving unit to move the object by enhanced friction forces.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the passive surface is a vacuum table.

Furthermore, in accordance with a preferred embodiment of the presentinvention, there is provided a dual-sided non-contact support platformfor supporting without contact an object by air-cushion induced forces,the platform comprising:

-   -   two substantially opposite support surfaces, each support        surface comprising at least one of a plurality of basic cells        having at least one of a plurality of pressure outlets and at        least one of a plurality of air-evacuation channels at least one        of a plurality of outlets, and one of a plurality of        air-evacuation channels, each of the pressure outlets        fluidically connected through a pressure flow restrictor to a        high-pressure reservoir, the pressure outlets providing        pressurized air for generating pressure induced forces,        maintaining an air-cushion between the object and the support        surface, the pressure flow restrictor characteristically        exhibiting fluidic return spring behavior; each of said at least        one of a plurality of air-evacuation channels having an inlet        and outlet, the inlet kept at an ambient pressure or lower,        under vacuum condition, for locally discharging mass flow, thus        obtaining uniform support and local nature response.

Furthermore, in accordance with a preferred embodiment of the presentinvention, each of the air-evacuation channels is connected to a vacuumreservoir.

Furthermore, in accordance with a preferred embodiment of the presentinvention, each of the air-evacuation channels is connected to a vacuumreservoir through a vacuum flow restrictor, the vacuum flow restrictorcharacteristically exhibiting fluidic return spring behavior.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the two substantially opposite support surfaces aresubstantially symmetrical.

Furthermore, in accordance with a preferred embodiment of the presentinvention, a gap between the two substantially opposite support surfacesis determined to be at least the width of anticipated object to besupported within plus twice the desired air-cushion gap.

Furthermore, in accordance with a preferred embodiment of the presentinvention, a preload mechanical spring is provided to adjust the gapbetween the two substantially opposite support surfaces in a paralleland self adaptive manner, and limit the forces induced on the twosubstantially opposite support surfaces to below a predeterminedthreshold.

Furthermore, in accordance with a preferred embodiment of the presentinvention, pressure supply or vacuum to one of the two substantiallyopposite support surfaces is different from the pressure supply orvacuum supply to the second of the two substantially opposite supportsurfaces, so that the levitation of the object between the twosubstantially opposite support surfaces may be adjusted to any desiredgap in between the surfaces.

Furthermore, in accordance with a preferred embodiment of the presentinvention, there is provided a system for conveying without contact asubstantially flat object, the system comprising:

-   at least one of two substantially opposite support surfaces, each    support surface comprising at least one of a plurality of basic    cells having at least one of a plurality of pressure outlets and at    least one of a plurality of air-evacuation channels at least one of    a plurality of outlets, and one of a plurality of air-evacuation    channels, each of the pressure outlets fluidically connected through    a pressure flow restrictor to a high-pressure reservoir, the    pressure outlets providing pressurized air for generating pressure    induced forces, maintaining an air-cushion between the object and    the support surface, the pressure flow restrictor characteristically    exhibiting fluidic return spring behavior; each of said at least one    of a plurality of air-evacuation channels having an inlet and    outlet, the inlet kept at an ambient pressure or lower, under vacuum    condition, for locally discharging mass flow, thus obtaining uniform    support and local nature response;-   driving mechanism for driving the object over said at least one of    two substantially opposite support surfaces;-   handling means for handling the object during loading or unloading    of the object onto said at least one of two substantially opposite    support surfaces;-   sensing means for sensing properties selected from the group of    properties including: position, orientation, proximity and velocity    of the object; and-   controller for controlling the position, orientation and traveling    velocity of the object over said at least one of two substantially    opposite support surfaces and communicate with a process line    adjacent the system.

Furthermore, in accordance with a preferred embodiment of the presentinvention, loading and unloading zones are provided.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the system comprises several one-sided types of said at leastone of two substantially opposite support surfaces.

Furthermore, in accordance with a preferred embodiment of the presentinvention, one of the several one-sided types of said at least one oftwo substantially opposite support surfaces comprises a PV supportsurface for providing flattening of the object, where at central zone ofthat PV support surface a processing on the object is conducted.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the PV support surface is provided with a relaxation zone onedges of the PV support surface having a relaxation length of about 5-15lengths of basic cells.

Furthermore, in accordance with a preferred embodiment of the presentinvention, further comprising at least one of a plurality of dual-sidedtype of said at least one of two substantially opposite supportsurfaces.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the dual-sided type of said at least one of two substantiallyopposite support surfaces comprising PP-type dual-sided support surfacesfor high flattening performance.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the dual-sided type of said at least one of two substantiallyopposite support surfaces comprising PV-type dual-sided support surfacesfor high flattening performance.

BRIEF DESCRIPTION OF THE FIGURES

In order to better understand the present invention, and appreciate itspractical applications, the following Figures are provided andreferenced hereafter. It should be noted that the Figures are given asexamples only and in no way limit the scope of the invention as definedin the appending claims. Like components are denoted by like referencenumerals.

FIG. 1 illustrates an electric-circuit analogy of a PA-type air-cushion,in accordance with the present invention.

FIG. 2 a illustrates a typical arrangement for a active-surface of aPA-type platform, in accordance with a preferred embodiment of thepresent invention.

FIG. 2 b is a chart illustrating the behaviour of a PA-type air-cushion.

FIG. 3 illustrates an electric-circuit analogy of a PV-type air-cushion,in accordance with a preferred embodiment of the present invention.

FIG. 4 a illustrates a typical arrangement for the active-surface of thePV-type platform.

FIG. 4 b illustrates the functionality of the PV-type air-cushion

FIG. 5 illustrates an electric-circle analogy of the PP-typeair-cushion.

FIG. 6 a illustrates a typical arrangement for the active-surface of thePP-type platform.

FIG. 6 b illustrates the functionality of the PP-type air-cushion

FIG. 7 illustrates a typical Self Adaptive Segmented Orifice (SASO) tobe used as the preferred flow-restrictor (PRIOR ART)

FIG. 8 a illustrates a basic PA-type non-contact platform.

FIG. 8 b illustrates a PA-type non-contact platform with evacuationgrooves.

FIG. 8 c illustrates a basic PA-type non-contact platform consisting oftwo segments.

FIG. 9 a illustrates a PV-type non-contact platform with only pressureflow-restrictors and a supported object that fully covers the platform'sactive-area.

FIG. 9 b illustrates a basic PV-type non-contact platform with bothvacuum and pressure flow-restrictors where the supported object is muchsmaller than platform's active-area.

FIG. 9 c illustrates a basic PV-type non-contact platform consisting oftwo segments.

FIG. 9 d illustrates a basic PV-type non-contact platform where thepressure and vacuum flow-restrictors are arranged in parallelalternating lines.

FIG. 9 e illustrates a basic PV-type non-contact platform used to holdor convey objects beneath it.

FIGS. 9 f-9 h illustrate some basic embodiments of carriages with activePV-type non-contact surfaces designed to be supported or conveyed over aflat track, or be suspended without contact from such track.

FIG. 10 a illustrates a single active-surface of a basic dual-sidedPP-type non-contact platform.

FIG. 10 b illustrates a single active-surface of a basic dual-sidedPP-type non-contact platform consisting of two segments.

FIG. 10 c illustrates a single active-surface of a basic dual-sidedPP-type non-contact platform with surface air-evacuation grooves.

FIG. 10 d illustrates a basic dual-sided PP-type non-contact platform.

FIG. 10 e illustrates a dual-side PP-type non-contact platform consistof two segments

FIG. 10 f illustrates the PP-type non-contact dual-side platform in avertical orientation.

FIG. 11 a illustrates a basic dual-sided PV platform.

FIG. 11 b illustrates a basic PM-type platform.

FIG. 12 illustrates various alternative embodiments of a PM-typenon-contact platform.

FIG. 13 illustrates a layered-structure of a typical active-surface.

FIG. 14 a illustrates a nozzle-plate with a plurality of pressureflow-restrictors.

FIG. 14 b illustrates a nozzle-plate with a plurality of pressure andvacuum flow-restrictors.

FIG. 15 a illustrates an integrated single manifold embodiment of atypical active surface with only pressure flow restrictors, andcross-sectional views.

FIG. 15 b illustrates an integrated double-manifold embodiment of atypical active surface with pressure and vacuum flow restrictors, andcross-sectional views.

FIG. 16 illustrates a typical non-contact conveying system.

FIG. 17 illustrates a one-side high-performance system.

FIG. 18 illustrates a dual-side high-performance system.

DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS

The significant configuration with respect to the present invention isthe case where the air-cushion is provided by an “active” platform andthe object over it is supported without motion or conveyed over thatplatform. Without derogating the generality, in most of the casesdescribed in this specification this configuration is usually referredto, but other possible configurations where the platform is passive andthe air-cushion is generated by an object having its own “activesurface” generating the air-cushion are considered to be covered by thepresent invention. Hereinafter, this second configuration is referred toas the “active carriage configuration”.

The present invention discloses novel non-contact platforms orequipments that make use of various types of air-cushions. A singleaerodynamic building block links the various types of air-cushions,namely the usage of a plurality of fluidic return springs to establisheda high performance non-contact platform. It is asserted that for betterperformance of air-cushion support systems, it is important to deal withthe evacuation of air from over the active surface. Without derogatingthe generality, the following types of air-cushions are disclosed, eachhandling the evacuation of air in a different manner:

Pressure-Air (PA) Type Air-Cushion

According to a preferred embodiment of the present invention, PA-typeair-cushion is generated using an active surface with a plurality ofpressure ports, and evacuation vents, where air is allowed to evacuateinto the surroundings. The PA-type air-cushion is preloaded by theobject bodyweight, where an object is supported by the non-contactplatform that balances the gravity forces. The PA-type platform providesnon-contact support in both cases where the object, that in common casesis flat and/or thin and/or of wide-format, is stationary supported orwhile it conveyed by any drive mechanism. The lateral dimensions of theobject are usually much larger than the dimensions of the “basic cell”of the PA-platform to be discussed hereafter. “Bodyweight preloading”means that aerodynamic stiffness (to be referred hereafter byAD-stiffness), of the PA-type air-cushion at a predetermined equilibriumfloating gap (to be referred hereafter as the air-cushion nominal gap,denoted by ε_(n)), depends on the object weight. “AD-stiffness” meansthe amount of force that is developed by the air-cushion in aself-adaptive manner, when trying to change the nominal gap (between thelower surface of the object and the active-surface of the non-contactplatform). The AD-stiffness is measured, for the purposes of the presentinvention, in terms of grams/cm²/μm.

PA-type air-cushion is generated in a narrow gap between the activesurface of the platform and the supported object lower surface. The airis introduced to the air cushion by a plurality of pressure ports 12,provided with flow restrictors, preferably arranged in two dimensionalmanner or optionally at a mixed repeatable format with a plurality ofevacuation holes 14, through which excessive air evacuates into thesurrounding atmosphere. FIG. 2 a shows a typical rectangular format thatis very practical, and it also defines the repeatable “basic-cell” 10 ofthe PA-type air-cushion. The dimensions of the basic cell are selectedwith respect to the lateral dimensions of the object to be levitated,and in general it is desired that the resolution of the pressure portsand evacuation vents (all termed herein as holes) be such that at anygiven time a plurality of holes is covered by the levitated object. Toobtain uniform support of local nature, it is preferable that aplurality of basic-cells will be distributed in two-dimensional mannerto support the object. The PA-type air-cushion can be described by ananalogous electric-circuit (where the current is the mass flow rate, theresistors are the flow-restrictors and the electricity-potential is thepressure), as shown in FIG. 1. It has to be emphasized that the“resistor-symbol” used for the flow-restrictor hereafter is only ofsymbolic meaning and the embodiment details of the flow-restrictors suchas the preferred SASO-nozzles were described in WO 01/14782, WO 01/14752and WO 01/19572, all incorporated herein by reference. With respect tothis figure, R_(noz) represents the Fluidic-Return-Spring (to bereferred hereafter as FRS), flow-restrictors of the non-contactplatform, and with respect to a preferred embodiment of the presentinvention, SASO-nozzles will be applied as the FRS flow-restrictors.R_(ac) symbolized the aerodynamic-resistance (or shortly,AD-resistance), of the air-cushion, having a dynamic nature. P_(In) isthe supply pressure, P_(ac) is the pressure introduced to theair-cushion by the flow-resistors, P_(atm) is the ambient or theatmospheric pressure and ΔP is the pressure drop along theflow-restrictor R_(noz). MFR is the mass flow rate. This analogyclarifies that the flow of the PA-type air-cushion is controlled by twoserial flow-restrictors R_(noz) and R_(ac). R_(noz) is a solidrestrictor such as SASO-nozzle characterized by MFR that is dependent onthe inlet and the outlet pressures, P_(in) and P_(ac). R_(ac) is arestrictor that depends on (1) the aero-mechanic geometrical parametersof each specific design. It includes parameters such as the details ofthe flow-restrictor exit at the active-surface of the platform and theresolution of the plurality of FRS flow-restrictors (or the typicaldistance between neighboring flow-restrictors), (2) Operationally,R_(ac) depends on the air-cushion gap in a local and a temporal, thusR_(ac) is a dynamic flow-resistors whose aerodynamic resistance dependson the air-cushion gap. Accordingly, when an object faces theactive-surface of the platform and an air-cushion is established, thepressure introduced to the air-cushion P_(ac) as well as the MFR arealso controlled by the air-cushion gap that may be off-seted dynamicallyby an external force or due to interaction with the object that is inmotion or due to any other reason. Off-set of the air-cushion gap mustbe considered also in a local manner.

The functionally of the PA-type air-cushion is associated with gravity.In an undisturbed equilibrium state (see FIG. 2 b, equilibrium case),where, for example, about half of the pressure supply (P_(in)) isintroduced to the air-cushion (P_(ac)), and accordingly ΔP is of thesimilar value, the object is supported by the PA-type air-cushion atε_(n) where the average pressure force (ΣF_(p)) that is developed by theair-cushion balances gravity. A practical set-up would involve pressureflow restrictors over which some 30%-70% of the supplied pressure isdelivered to the active-surface, through the pressure outlets. Whentrying to close the gap (see FIG. 2 b, off-set down case), theaerodynamic-resistance of the air-cushion (R_(ac)) increased, thus morepressure is introduced by the flow-restrictor R_(noz) to theair-cushion, as a portion of the ΔP is discharged since MFR is reduced.Consequently, the increased ΣF_(p) pushes, like a two-dimensionalspring, the object up to equilibrium at ε_(n). On the other hand, whentrying to open the gap, (see FIG. 2 b, offset up case), the air-cushionaerodynamic-resistance (R_(ac)) is decreased and P_(ac) decreases andMFR and ΔP are increased. Consequently, gravity pulls the object down toε_(n). as it is a two directional behavior, but of asymmetric response,It is stated hereafter that the AD-stiffness of the PA-type air-cushionis of one-directional nature because only lifting force that is equal tothe object weight is needed to take the object away from the platformbut when trying to push it down to contact with the active-surface ofthe platform, aerodynamic counterforce that can be many times largerthan the object weight is exerted by the PA-type air-cushion to ensureno contact.

A PA-type non-contact platform is preloaded by the object bodyweight. Ingeneral, as the pressure introduced to the air-cushion is higher, theAD-stiffness is intensified. It means that a well-functioningnon-contact platform in terms of air-cushion stiffness, a stable andeasy to-controlled platform, is obtained when the object is heavy, andrelatively high pressure (P_(ac)), has to be introduced to theair-cushion in order to balance gravity. A “non-contact guaranteed”safety feature, may be achieved by using large pressure supply (P_(in)),to increase the ΔP inside the flow-restrictor R_(noz), thus R_(noz) mustbe of large AD-resistance In such an operational conditions, thepotential to developed high return forces with respect to the objectweight is obtained when trying to close much of the air-cushion gap. Atsuch a large offset from ε_(n), ΔP is discharged and P_(ac) issignificantly increased. Consequently, large FRS forces that can be manytimes larger than the object weight is developed and guarantees nocontact. It has to be mentioned with respect to the PA-type air-cushionthat in order to relieve most of the ΔP potential to guaranteeno-contact, it is not necessary to close the gap because theAD-resistance of R_(ac) rapidly grows as the gap is narrowed. Typically,the nominal equilibrium floating gap (ε_(n)) of PA-type air-cushion isin the range of 50-1000 μm, with respect to many of the applicationsmentioned herein, where the lower the desired ε_(n), the smaller the MFRsupply that is needed.

When it is required to support or to convey flat and thin low-weightobjects, such as wafers or FPDs, a well functioning air-cushion supportmust not be simply related to (ultra-light) bodyweight preloading. Suchobjects that are also flexible to some extent (with respect to its largelateral dimensions), typically have a bodyweight distribution of about0.3 gram/cm² (thus an average pressure of 0.3 millibars is enough tosupport such a flat objects), In case of supporting printing worldmedia, the bodyweight can be much more smaller. It means that in orderto provide a well functioning non-contact platform, extremely highoperational pressure with respect to object weight must be introduced tothe air cushion but still the average supporting pressure should befairly small to support such a low-weight objects. Therefore, withrespect to preferred embodiments of the present invention, the “fingertouch” approach is introduced to provide high performance and wellfunctioning non-contact platform that is based on the PA-typeair-cushion. The “finger touch” approach is applied by distributingevacuation holes or by creating evacuation grooves, or both, at theactive-surface of the non-contact platform. The purpose of local airevacuation is to introduce the ambient pressure in close vicinity to theoutlets of each of the flow-restrictors, that are evenly distributed onthe non-contact platform. In such way, at nominal conditions, thepressure introduced to the air-cushion is high only at a smalleffective-zone around each of the flow-restrictors exits and rapidlydecays in a circumferential manner, and the out-coming flow is locallyevacuated to the ambient atmosphere through the closest evacuatingholes. When both flow restrictors and evacuation holes (or grooves) aredistributed in any well-organized manner, homogenous support isobtained. For example, it is very practical (see FIG. 2 a), to use achess-table format where the flow-restrictors are placed at the centerof the (imaginary) white squares and the evacuation-holes at the centerof the (imaginary) black squares. At such arrangement, the air-cushionbecomes like a nail-bed having supporting fingers of high pressure andmost of the active-surface of the non-contact platform is notcontributing a significant support at nominal conditions.

To discuss the functionality of a PA-type air-cushion that implementsthe “finger touch” approach, reference is made to FIG. 2 b. Whenapplying the “finger touch” approach, AD-stiffness of the PA-typeair-cushion is significantly intensified. When trying to close theair-cushion nominal gap (ε_(n)) the air-cushion dynamically responds intwo complementary aspects: first of all, FRS flow restrictors providesit's portion where the high ΔP of the flow-restrictor is discharged andthe pressure introduced to the air cushion P_(ac) is significantlyincreased. Simultaneously, the global effective-area (which is thecontributions of all the local effective-zones around the exits of theflow-restrictors), is rapidly increased (see FIG. 2 b, offset downcase). The pressure extended redistribution occurs close to the outletsof the flow-restrictors, where the high pressure around the outletsoccupied more area as the offset down from the ε_(n) is larger.Accordingly, AD-stiffness is significantly amplified due to both FRSflow-restrictors and pressure redistribution inside the air-cushion. Theimplementation of the finger-touch approach and the beneficial use ofthe effective-area self-adaptive response, which is associated with thatapproach, provide a behavior that is disassociated from the objectbodyweight. In-addition, when using high pressure supply that can be aslarge as 100 to 1000 times more than the average pressure needed tosupport a low weight object (for example, P_(in) can be 30 to 300millibars for objects of bodyweight of about 0.3 gram/cm²), no-contactis ensured and a stable and easy-to-control non-contact platform isobtained. It also reduces risks of local contact when the object is notperfectly flat, as it locally resists to local changes of the gap bygenerating extremely high upper-wise local forces. The finger touchapproach is also of significant importance in case of supporting lowweight objects. The finger touch approach also provides significantadvantages when aiming at supporting heavy objects, in particular withrespect to the safety factors of “non-contact guarantee” requirements,where the PA-type air-cushion performances must be valuated in terms oflocal-nature performances.

It is important to emphasize that when applying the “finger touch”approach, the non-contact support of the PA-type air-cushion isessentially not sensitive to the object bodyweight, thus as the objectweight is increased, the resulting changes in ε_(n) are small (theobject slightly lowers down). A well designed non-contact PV-typeplatform must also fulfil the requirement for low sensitivity to theobject's lateral dimensions. The PA-type platform must also functionwell in common cases where the object has small lateral dimensions withrespect to the platform active-surface and it covers only a portion ofthe active-area, or when the object travels over the platform and a part(even a substantial part) of the active-surface is not coveredtemporarily. The PA-type air-cushion provides such a requirement whereonly minor changes in the ε_(n) due to insignificant lateral chances ofthe supply pressure P_(in) when significant portion of the platformactive-surface is not covered. First of all and most effective way ofproviding such low-sensitivity support is the use of flow-restrictorssuch as SASO-nozzles that prevent excessive mass flow as the alreadydescribed aerodynamic blockage mechanism of the SASO-nozzlessignificantly limits the flow at the uncovered areas. Secondly, It isalso directly connected (a) to the “finger-touch” approach that enablesthe working with high P_(in) (b) to the use of a plurality offlow-restrictors having large AD-resistance (such as SASO-nozzles) touse large ΔP. Practically, both prevent lateral gradients inside thepressure reservoir that feeds the flow-restrictors, thus each of theflow restrictors operates individually with no interactions by upstreaminfluences on the reservoir pressure, with the other existingrestrictors.

Another important feature of the Pa-type platform of the presentinvention is the “local-balanced” high quality support that ischaracterized by a uniform air-cushion support with no global effects,and self-adaptive behavior of local nature. When (a) the supportedobject is of a wide-format, flat and thin and optionally flexible tosome extent (such as 200×180 cm FPDs or wafers), and when (b) it isintended to support or to convey such an object by a PA-type non-contactplatform having a plurality of flow-restrictors such as SASO-nozzles andwhen (c) there is no local evacuation of flow, then the object issupported in a global malfunctioning manners. It that case, the flow canbe evacuated only at the edges of the active-area, which is the actualdynamic overlapped area between the object lower surface and theactive-surface of the platform, thus lateral flow from the centralsupporting areas must exist and accordingly the air-cushion support isinherently of non-homogenous nature. In that case (a) P_(ac) developedat the central-areas is higher than the P_(ac) found close to the edgesof the active-areas, thus (b) when the object is flexible (in respect toits lateral dimensions), a non-uniform levitation gap of the dimensionalcharacter is established, causing the object to significantly deformconvexly, as the central-area is lifted to a higher levitation gap withrespect to the levitation gap at the edges of the levitated object,Accordingly (c) the AD-stiffness at central area deterioratesdramatically or even vanishes when P_(in)=P_(ac), and (d) when thecentral area of the object is over-lifted, much more MFR is needed tomaintain the air-cushion. Consequently, a malfunctioning inhomogeneousnon-contact platform is obtained, a situation that may damage thelevitated object, or it may not meet the requirement to keep theflatness of the object within small allowable tolerance.

According to a preferred embodiment of the present invention, awell-functioning PA-type non-contact platform can be obtained byadopting the “local balanced” approach, to be implemented by using localevacuation by holes and/or grooves. When local evacuation is establishedand the flow-restrictors are homogenously arranged in a repeated patternof similar basic-cells of local nature, it provides a “local balanced”uniform PA-type air-cushion support; where as the smaller the basic-cellis, the more uniform the air-cushion characteristics are. In such alocally balanced situation, the out-coming flow from each of the flowrestrictors is discharged though the neighboring evacuation elements.Accordingly, a PA-type non-contact platform designed according to thelocal balance approach is a well functioning air-cushion where thestiffness, the pressure, the force, and the MFR are equally distributed,as long as the dimensions of the basic-cell are substantially smallerwith respect to the actual active-area excluding it's edges-area. Thelocal balance approach provides homogeneous support with no damage tothe object and a capability to keep the flatness of the object withinthe required tolerance.

Both the local-balance and the finger-touch approaches are implementedby making local evacuation holes or outlets. With respect to severalpreferred embodiments of the present invention, the basic-cell mayincludes (a) one evacuation vent for each of pressure port. It is verypractical to use the already described chess format arrangement (seeFIG. 2 a). (b) more than one evacuation hole for each of pressure port(c) more than one pressure port for each of the evacuation holes.Evacuation grooves can be considered too, (d) surface grooves with endsat the edges of the active-surface platform, and/or (e) making limitednumber of evacuation holes inside the surface grooves. Evacuation can beachieved partly or solely through the edges of the platform'sactive-surfaces. (f) In general, any practical combination of evacuationholes and/or grooves and/or edge-evacuation can be considered.

With respect to another prefer embodiments of the present invention, itis an option to (a) divide the active surface of the non-contactplatform (in a one-dimensional manner), into several separated elongatedactive surfaces thus local evacuation at internal active-surfaces can beobtained, at least partly, through the edges of each of the elongatedactive-surfaces. (b) The surface of the non-contact platform can bedivided also in a two-dimensional manner, Where the active-surface isdivided into several separated rectangular sub-surfaces, to provideinternal evacuation through the edges.

The PA-type platform can be configured in any practical way. Accordingto another prefer embodiments of the present invention, (1) It ispractical to configure rectangular configuration for a non-contactPA-type platform, that can be also a section of a greater non-contactsystem, for example when the platform is used to support or convey FPDs,(2) PA-type platform can be provided in a circular active-surface shapeto support, for example, wafers in both cases where the wafer is in restor in rotational motion. It can be beneficial also to use a circularPA-type platform for a turning a sub-system where a rectangular objectsuch as FPD is supported with no-contact and have it reoriented by anymechanical means.

The resolution of the basic-cell or the number of pressure ports at theplatform's active-surface affects the manufacturing cost. Highresolution indeed provides high level of homogenous support but thestiffness can be weakened. Therefore the resolution must be specifiedwith respect to the lateral dimensions of the anticipated supportedobject, and it's elastic properties that directly relate also to it'slateral dimensions and width. Accordingly, resolution must be specifiedwith respect to the requirements of a specific application in mind. Withrespect to other preferred embodiments of the present invention (a) insome cases it is recommended to increase the resolution only at only aportion of the platform active-surface to provide better performancelocally, where the specification demands it, (2) it is recommended toincrease the resolution close to the edges of the active-surface thusreducing the lateral scale of the edge effects (the air-cushion decaysin a lateral direction that is normal to the edges), to improveedge-area performances. Typically, holes spacing in the range of 10-60mm for the PP-type platform covers most practical applications. Inanother preferred embodiment of the present invention, the pressuresupply to the areas that are close to the edges of the actives-surfaceof the PA-platform is larger from the rest of the platform in order toimprove the edges' local performance. Typically, 400-2000flow-restrictors are used per square meter and MFR of each of theflow-restrictors at pressure supply of about 100 millibars is in therange of 0.2-0.8 Nlit/min for a wide format active surface, thus theoverall MFR needed is significany small with respect to operationalcost-performance.

In particular, when processing is taking place while the object issupported in rest or conveyed by a PA-type platform, with respect toanother prefer embodiments of the present invention, the PA-typeplatform active-surface can be divided into two or more sections toassist the process. The space created between two sections can be aswide as 10-100 mm across the direction of motion, usually withouthurting the natural flatness of the object (depending on the elasticityof the object). Sub-surfaces can also be created in two-dimensionalmanner for any practical reasons, Such an inter-sections space can beuseful in the following manners: (1) It becomes possible to assist theprocess from its bottom side as the process takes place on the topsurface of the object, that may be stationary, continuously moved ormove at a step-by-step motion). Assistance by any source of light forillumination or imaging, laser beam of any power, as well as heating byradiation or by hot air flow are only a few practical examples. (2) Itprovides an option to perform, a dual-side process, optionallysimultaneous, at both the upper and the lower surfaces of the objectwhile it is conveyed over the non-contact platform. In addition, (3)when a low-cost conveying system is considered, sectional active-surfaceto provide non-contact to only parts (20-60%) of the object bottomsurface can be both suitable and very cost effective.

With respect to another prefer embodiments of the present invention, (a)it is possible to create a system where the object is supported orconveyed with non-contact, part of the time but at the rest of the timeit changes it's functionality and becomes a vacuum table to holds downthe object in-contact for any practical reasons. It can be done byintroducing vacuum instead of pressure to the platform active-surface'sholes. Such a system can supports or convey an object without contact,or grip the object in-contact by vacuum, objects that are much smallerthan the platform's active-area, due to the aerodynamic blockagemechanism that provides by flow-restrictors such as SASO nozzles thateffectively limits the MFR in uncovered active-areas. When switchingback to pressure, the recommended SASO flow-restrictors rapidly limitthe flow, to provide soft disconnecting process. (2) Such a soft processcan be applied in vacuum tables systems as a non-contact landing anddisconnecting mechanism. It is established by switching to pressure whenat the loading phase, switching to vacuum for landing and holding theobject in contact during the process and switching back to pressure tosoftly disconcert the object at the unloading phase. The switchingbetween vacuum and pressure can be carried out rapidly, when using alow-volume integrated manifold with the pressure reservoir.

With respect to another prefer embodiment of the present invention, thehigh performance PA-type air-cushion can be used, for example (as alow-cost replacement to air-bearing non-contact technology that commonlymakes use of several air-bearing pads), to support a heavy stage or acarrier, (frequently made of granite), usually found in the productionline's process-machines found at the semiconductor industry or at theFPD fabrication lines. Operationally, The differences between the airbearings and the air-cushion are: (1) air-bearings practical floatinggap is in the range of 3-20 micrometers while the PA-type air-cushiontypical range is 50-1000 micrometers, thus air-bearing can be appliedonly when two extremely smooth confronting surfaces are involved. (2)air-bearing equipment uses high operational pressure (1-10 bars, but inmany cases about 5 bars above the ambient pressure), whereas the Pa-typeair-cushion operational pressure is much lower, typically in the rangebetween 10-500 millibars. Although we consider so far only flatconfigurations of the PA-type platform, the active-surface with respectto such applications, can be laterally “v” shaped or of cylindricalshape (when elongated active-surface is considered), in order toestablished a naturally stable non-contact mechanism to avoid, in aself-adaptive aerodynamic nature, lateral movements.

With respect to another preferred embodiment of the present invention,It is an possible to use a sectorial pressure manifold where thepressure is individually controlled at each sector. It Provides localcontrol of the pressure introduced to the air-cushion (P_(ac)), oralternatively speaking, it provides a mechanism to adjust the nominalgap ε_(n), thus the flatness accuracy may be locally improved. Thenon-contact platform can include any practical division to sectors, inan one-dimensional or two-dimensional arrangement.

Pressure-Vacuum (PV) Type Air-Cushion

According to a preferred embodiment of the present invention, PV-typeair-cushion is generated using an active surface with a plurality ofpressure ports, and evacuation outlets connected to a vacuum source,thus excessive air is evacuated by that vacuum.

According to another preferred embodiment of the non-contact platform ofthe present invention, the PV-type air-cushion is introduced. It is avacuum preloaded air-cushion where the object is accurately supported inrest or conveyed while gripped by the PV-type air-cushion. TheAD-stiffness of the PV-type air-cushion is inherently of bi-directionalnature and it may not be depended on the object bodyweight.Bi-directional stiffness means that in both cases when trying to pushthe abject toward the active-surface of the non-contact platform or whentrying to pull it away from that surface, AD-forces that can be muchlarger than the object bodyweight force the object back, in aself-adaptive manner, to the equilibrium nominal gap. The objectdimensions can be much smaller than the active-surface of the platform.Accordingly we shell refer to the expression active-area as the area onthe active-surface of the platform where the object subsists.

PV-type air-cushion generally includes two types of conduits, frequentlyarranged in a repeatable chess-table format above the active surface ofthe non-contact platform as shown in FIG. 4 a, where outlets of pressureconduits 18 are placed at the center of each of the white squares andone outlets of vacuum suction conduits 20 are placed at the center ofeach of the black squares. The repeated “basic cell” 16 of the PV-typenon-contact platform is also shown in this figure. The pressure conduitsare always individually equipped with flow-restrictors, preferablySASO-nozzles, to provide the FRS local behavior of the non-contactplatform and to secure, by implementing the aerodynamic blockagemechanism, the uniformity of pressure supply in cases where the activesurface of the platform is not fully covered. the vacuum conduits aresimple cylindrical hole or Optionally, they may also equipped with anindividual flow-restrictors such as SASO-nozzles, but it must be of muchlower AD-resistance with respect to the pressure flow-restrictors, inorder to secure the vacuum level by aerodynamic blockage mechanism inuncovered areas.

The pressure distribution of the PV-type air-cushion is aligned with thechess-table format arrangement of the pressure and vacuum conduitsdistributed over the active-surface of the PV-type platform. When thefacing surface of gripped object confronts the horizontal active-surfaceof PA-type platform in a small nominal gap (ε_(n)), and PV-typeair-cushion is established, the pressure is distributed around the oprtsof the pressure conduit and the vacuum is distributed around the outletsof the vacuum ports. Accordingly two opposing forces grips the objectand the difference between them balances the object weight. Due to theeffective use of different AD-resistance for the pressure and the vacuumconduits, PV-type air-cushion is characterized by different ranges ofinfluence away from the active-surface, where the global force inducedby the pressure (ΣF_(p)) has a shorter range of influence and theopposing global force induced by the vacuum (ε_(Fv)) has a longer rangeof influence. With respect to a preferred embodiment of the presentinvention, the PV-type non-contact platform provides such an unevenrange of influence, and it is the essential operational mode for thePV-type air-cushion. Although the PV-type platform induces forces fromonly one side, it grips, in fact, the object in a two-directional mannerand resists aerodynamically to any (up or down) offset from ε_(n) in asself-adaptive and local manner. This significant behavior is theimportant character of that non-contact platform, and it stands in bothcases, whether the vacuum conduit is equipped with a flow-restrictor ornot, because in both cases the AD-resistance of the vacuum conduits ismuch lower than the AD-resistance of the pressure conduits that areunconditionally equipped with a flow-restrictor such as SASO nozzle. Ithas to be emphasized that the bi-directional behavior providesbi-directional AD-stiffness, to be the essential and the most importantproperty PV-type air-cushion.

PV-type air-cushion can be analogously described by an electric-circuit(see FIG. 3). R_(noz) represents the FRS flow-restrictors, which arepreferably SASO-nozzles, R_(ac) symbolized the dynamic AD-resistance ofthe narrow air-cushion, R_(vnoz) represents the vacuum flow-restrictors(preferably SASO-nozzles) optionally provided inside the vacuumconduits. P_(sup) is the supply pressure and P_(ac) is the pressureintroduced to the air-cushion. V_(sup) is the supply vacuum and V_(ac)is the vacuum introduced to the air-cushion. MFR is the mass flow rate.ΔP is the pressure drop along the restrictor R_(pnoz). ΔV is the vacuumdrop along the restrictor R_(vnoz) if exists (and if not ΔV=0). Thisanalogy clearly indicates that the flow of the PV-type air cushion iscontrolled by three serial flow restrictors R_(pnoz), R_(ac) and,optionally, R_(vnoz), R_(pnoz) and R_(vnoz) are different solidflow-restrictors such as SASO-nozzles of different characteristics(means a MFR that is depended on P_(sup) and P_(ac) at the pressure sideand on V_(sup) and V_(ac) at the vacuum side). As the through MFR arethe same, ΔP and ΔV are dynamically adjusted in a self-adaptive mannerto obey the requirement for continuity. R_(ac) is a flow-restrictor thatdepends on the dynamic air-cushion gap ε. (for more details see therelevant text on the PA-type air-cushion). Accordingly, R_(ac) is adynamic flow-resistor whose AD-resistance depends on the air-cushiongap, and when an air-cushion is established, the pressure and the vacuumintroduced to the air cushion, as well as the MFR, are also controlledby ε which is also the gap between the active surface of the platformand the confronting surfaces of the supported object.

It is possible to provide a flow restrictor in the air-evacuation ventswhich are fluidically connected to the ambient atmospheric pressure,without connecting it to a vacuum source, thus in effect the pressure ofthe air-cushion and hence the lifting force under the object areincreased. It would be natural to call these flow restrictors“air-evacuation flow restrictors”, but in order to simplify the term“vacuum flow restrictor is used throughout this specification to referto air-evacuation flow restrictors too.

According to a preferred embodiment of the PV-type platform, thefunctionality of the PV-type air-cushion may not be related to gravity.In an equilibrium gripping state (ε_(n)), the object is supported by thePV-type air-cushion where the total pressure forces (ΣF_(p)), which aredeveloped around each outlet of the pressure restrictors R_(pnoz)(preferably SASO nozzles), are of the same order of magnitude as thetotal opposing vacuum forces (ΣF_(v)) that are developed around eachoutlet of the vacuum conduits, which may optionally be equipped withdifferent flow-restrictors R_(vnoz) (but preferably SASO nozzles). Bothopposing forces may by larger by a factor of 10 or 100 and more from theobject bodyweight, and the differential force (ΣF_(p)−ΣF_(v)) balancesthe gravity. In such magnitudes, the functionality of the PV-typeair-cushion, with respect to AD-stiffness and accordingly to theflatness accuracy performances, is disassociated form the object weight.It has to be emphasize again that the PV-type air-cushion hasessentially bi-directional AD-stiffness that does not depend on theobject weight, and it is a most important property of the PV-typeplatform, for it means that in both cases when trying to push the objecttowards the active-surface of the platform or when trying to pull itaway, opposing aerodynamic forces are developed by the air-cushion in aself adaptive and local manner to return it to its equilibrium position.

According to a preferred configurations of the present invention, thePV-type platform can be configured in the following orientation withrespect to the direction of gravity: (a) A horizontally oriented objectcan be gripped from its bottom side by a horizontal active-surface ofthe PV-type platform, which is based on the PV-type air-cushion, where(ΣF_(p)−ΣF_(v)) balances the object weight, (b) A horizontally orientedobject can be gripped form it's upper side by a horizontalactive-surface of the platform above the object, where the(ΣF_(v)−ΣF_(p)) balances the object weight. It is also possible (c) togrip the object in a close gap to the active surface of the non-contactPV-type platform when the object's facing surface is not horizontallyoriented or is even vertically oriented with respect to gravity.

In order to understand the equilibrium state of the PV-type air-cushionreference is made to the configuration where the object is gripped fromits bottom side by the PV-type platform, equipped with a plurality ofboth pressure and vacuum (possibly different) flow-restrictors,distributed at a staggering chess-table format as shown in FIG. 4 a. Theflow is introduced to the air-cushion at a pressure P_(ac) through theoutlets of the pressure flow-restrictors, which are preferably SASOnozzles, placed in the white squares and the vacuum V_(ac) sucks air offthe surface through the outlets of the vacuum conduits equipped withflow-restrictors, which are, again, preferably SASO nozzles, placed atthe black squares. At equilibrium state, (see FIG. 4 b, equilibriumcase), the introduced pressure and vacuum (P_(ac) and V_(ac)) are almostthe same and distributed almost equally thus occupying similareffective-area. Yet, the differential lifting force (ΣF_(p)−ΣF_(v))balances the object weight. Hence the PV-platform performance isdisassociated from the object bodyweight, and ΣF_(p) and ΣF_(v) can besubstantially greater than the gravity force.

The dynamic characteristics of the PV-type air-cushion will be explainhereafter with respect to FIG. 4 b, illustrating the pressuredistribution along cross-section AA (see FIG. 4 a) in three differentstates—offset down, equilibrium and offset up. When trying to close thePV-type air-cushion nominal gap ε_(n), the AD-resistance of theair-cushion (R_(ac)) increases, reducing the MFR, thus more pressure isintroduced to the air-cushion by the flow-restrictor R_(pnoz), as aportion of the ΔP is discharged. Unfortunately, the vacuum introduced tothe air-cushion by R_(vnoz) also increases as a portion of the ΔV isdischarged. Consequently, a situation where a similar, potentiallyequal, increase in both the ΣF_(p) and the ΣF_(v) can be obtained,resulting with a degenerate PV-type non-contact platform with noAD-stiffness. Therefore, with respect to a preferred embodiment of thepresent invention, the AD-resistance of flow-restrictor R_(pnoz) must besignificantly larger than the AD-resistance of the flow-restrictorR_(vnoz). Accordingly, with respect to the MFR, ΔV must be much smallerthan ΔP. For-example, if a well functioning PV-type air-cushion isoperated at a typical P_(sup)=200 milibar and half of it is introducedto the air cushion (thus P_(ac)=100 milibar and ΔP=100 milibar), inorder to provide high AD-stiffness at Σ_(n), the introduced vacuumV_(ac)=100 milibar (under the assumption that the both counter-forcesare almost equally distributed), and in order to provide awell-functioning PV-type air cushion, the value ΔV must be not more thanhalf of the value of ΔP, and preferably 10%-30%. Practical value isΔV=20 milibar with respect to the example and accordingly V_(sup)=120milibar. Accordingly, the absolute value of the pressure supply may belarger by a factor of 1.2.-3 with respect to the absolute value of thevacuum supply. When using different aerodynamic resistance for R_(pnoz)and R_(vnoz), preferably two different SASO nozzles, and when trying tooffset ε_(n) (up or down), the pressure becomes more sensitive to suchoffsets with respect to the vacuum sensitivity. As the vacuumflow-restrictor is responsible for deteriorating the air-cushionperformance, providing flow-restrictors at the vacuum conduits isnecessary only when it is needed to avoid vacuum losses and waste of MFR(by applying the aerodynamic blockage mechanism when SASO nozzle areused), in cases where the active-surface of the platform is not-fullycovered at least during a potion of the operational time. Therefore, ifthe active-surface of the PV-type platform is fully covered and if thereare no restrictions attributed to the process or the loading andunloading phases, it is suggested, according to another preferredembodiment of the present invention, not to use flow-restrictors for thevacuum suction restrictors, The use of FRS SASO-nozzles (where theself-adaptive aerodynamic blockage mechanism is applied), for thepressure flow-restrictors R_(pnoz), also avoids pressure losses andwaste of MFR. And it is another good reason to work with SAOS-nozzles.

the rationale behind using different flow-restrictors for the pressureand the vacuum conduits was already explained hereinabove. the dynamiccharacteristics of a well functioning PV-type platform will be describedhereafter with respect to FIG. 4 b. The dynamic behavior of the PV-typeair-cushion is controlled by the gap ε. The AD-resistance of R_(ac) isvery sensitive to changes in s. Accordingly, changes occur in theintroduced pressure (P_(ac)) and vacuum (V_(ac)), and in the pressuredistribution inside the air-cushion. In particular, the changes in theinternal pressure distribution contribute significantly to amplificationof the AD-stiffness. When the PV-type air-cushion grips and supports anobject at the nominal equilibrium gap ε_(n), and with respect to apreferred operational mode of the present invention, it operates at evenoperational conditions, the value of P_(ac) is almost similar to thevalue V_(ac) and the area occupied by the pressure lifting forces ΣF_(p)is almost equal to the area occupied by the holding down vacuum forcesΣF_(v), as shown in FIG. 4 b, equilibrium case. In such an evensituation, and when ΣF_(p) and ΣF_(v) are both greater many times morewith respect to the object weight, the differential lifting force(ΣF_(p)−ΣF_(v)) stably supports the gripped object weight, which islevitated with high flatness accuracy at Σ_(n).

When trying to close the PV-type air-cushion gap ε_(n) (see FIG. 4 b,offset down case), the AD-resistance of the air-cushion (R_(ac))increases reducing the MFR, thus significantly more pressure P_(ac) isintroduced by R_(pnoz) as a portion of the ΔP is discharged, and thevacuum V_(ac) introduced by R_(vnoz) is only slightly increased as aportion of the ΔV discharged. This favorable uneven changes occur whenthe AD-resistance of pressure flow-restrictor R_(pnoz) is significantlylarger than the AD-resistance of vacuum flow-restrictor R_(vnoz), andaccordingly ΔP is much larger than ΔV, where both ΔP and ΔV may bereferred to as a pressure-potential—to be optionally delivered to theair-cushion. Simultaneously rapid changes with the air-cushion pressuredistribution take place, where the area occupied by the lifting pressureforces ΣF_(p) significantly increases and accordingly the area occupiedby the holding down vacuum forces ΣF_(v) significantly decreases asshown in the figure. Consequently high FRS forces push the object up,back to the ε_(n). On the contrary (see FIG. 4 b, offset up case), whentrying to open the PV-type air-cushion gap and create an up-wise offsetfrom ε_(n), the AD-resistance of the air-cushion (R_(ac)) decreases andthe MFR increases, thus significantly less pressure P_(ac) is introducedby R_(pnoz) as ΔP is increased, and the vacuum V_(ac) introduced byR_(vnoz) is only slightly increased as ΔV slightly decreases.Simultaneously significant changes with the pressure distribution takeplace, where the area that is occupied by the pressure forces ΣF_(p)significantly decreases and accordingly the area that is occupied by thevacuum forces ΣF_(v) significantly increases as shown in the figure.Consequently, high FRS forces pull the object down, back to the ε_(n).It has to be emphasized that the FRS forces are of self-adaptive andlocal nature.

The active-surface of the PV-type non-contact platform is provided withboth a plurality of pressure flow-restrictors to introduced the air tothe air-cushion, and vacuum conduits, optionally equipped with differentflow-restrictors, to suck the out-coming flow. Optionally, both arearranged in a chess-table repeatable format. In such a case, the PV-typeair-cushion is inherently of local balance nature. Accordingly, uniformgripping in all aspects of performance are naturally provided, thusno-global effect occurs. Therefore it is available to provide a PV-typenon-contact platform as wide as needed to grip an object of extremelylarge dimensions as it is accurately supported at rest or conveyed byany drive system. It has to be emphasized that the local nature and theuniformity are valid as long as the dimensions of the basic-cell (seeFIG. 4 a), of the PV-type air-cushion are significantly smaller withrespect to object lateral dimensions, and the locality and uniformityare no-longer valid at areas that are close to the edges of the activesurface of the platform. In order to reduce the damage of edge effects,with respect to another preferred embodiment of the present invention,it is favorable to increase the resolution (i.e. increase the density ofholes) near the edges of that active-surface thus reducing the edgeeffects on a lateral scale (the air-cushion decays in a direction thatis normal to the edges). Similarly, according to another preferredembodiment of the present invention, a differentiation will be made inthe pressure manifold and the pressure supply to areas that are close tothe edges of the actives-surface, will be larger than the pressuresupply to internal areas of the PV-type platform.

By implementation of vacuum preloading, the PV-type air-cushion providesan AD-stiffness of bi-directional nature, and it opposes, in a selfadaptive and local manner, any changes in ε_(n) both when trying to pushit towards, or when trying to pick it away from a horizontalactive-surface of the non-contact platform. In order to provide accuratefloating flatness, since the air-cushion support follows theactive-surface in common cases where the objects are of wide-format andflexible with respect to its width and lateral dimensions, the platformactive-surface must preferably be flat and manufactured with respect tothe required tolerances. If the object is rigid, the platform tolerancesare averages, but the risk of local contact may increase. Furthermore, auniform air-cushion floating gap is to be obtained by providing highAD-stiffness. Two straightforward parameters affect the stiffness (a) asthe pressure supply is higher and accordingly the MFR intensified,higher AD-stiffness is obtained. Without derogating the generality,practical values of pressure supply are 50-1000 millibars andaccordingly the practical vacuum level will be as much as half of thepressure level (b) as the predetermined ε_(n) is smaller, higherAD-flatness and accordingly increased flatness accuracy are obtained.Practically (for many of the applications mentioned hereinabove) Σ_(n)is in the range of 10-200 micrometers.

Typically, as the object to be supported is of large dimensions, or itis not elastic and when moderate accuracy is needed, ε_(n) and also thebasic-cell dimensions may be larger (less resolution). If the object isof small dimensions or it is elastic or when high flatness accuracy isneeded, narrower ε_(n) and smaller basic-cell dimensions (lessresolution) may be used. It has to be emphasized, that the smaller thebasic cell is, the higher the uniformity of the non-contact PV-typeplatform and vise-versa. With respect to other preferred embodiments ofthe present invention, (1) practical dimension of the basic cell thattypically includes four squares as shown in the figures are between12×12 mm to 64×64 mm. (2) It is also an option that the two dimensionsof the basic cell may not be of the same lengths. (3) It is also anoption that the basic cell will be of small dimensions in a restrictedareas where high performance is required with respect to high flatnessaccuracy, AD-stiffness and uniformity, whereas in other areas thedensity be smaller. (4) It is also very practical to use differentaspect ratio for the basic cells close to the edges of the active area,and to provide fine resolution to improve the local performance at theedges of the non-contact platform.

To obtain optimal performance, global aero-mechanic design of thenon-contact platform must be pedantically executed. With respect to apreferred operational mode of the PV-type non-contact platform of thepresent invention, The aero-mechanic design takes into account (1) theoperational conditions and the available MFR. (2) the characteristics ofthe flow-restrictors involved (in terms of the MFR vs. the input and theoutput pressure). (3) geometrical parameters such as the resolution orthe dimensions of PV-type air-cushion basic cell and the details of theoutlets of both the vacuum and the pressure conduits.

A PV-type air-cushion of high aerodynamic stiffness performance iscreated by two complementary components: (a) the use of a plurality ofpressure flow-restrictors, preferably SASO nozzles, serving as a FRS, toproduce opposing forces of self-adaptive and a local nature, by rapidlyincreasing/decreasing the pressure introduced to the PV-typeair-cushion, (the vacuum flow-resistors, if exist, reduce theAD-stiffness). (b) generating extreme changes in the air-cushionpressure distribution when offsets up or down in ε_(n) occur. Althoughthe implementation of FRS provides high AD-stiffness, extreme lateralchanges of the pressure distribution inside the air-cushion provide apotential to intensify the stiffness by a factor in a range of 2-5. Awell functioning high performance PV-type air-cushion is obtained as theAD-stiffness is large enough to provide high accuracy in terms of smallfloating gap tolerances (Δε_(n)). If also the active surface is flatwithin small tolerances, the PV-type platform provides non-contactgripping at high flatness accuracy when an object that is not rigidsupported at rest or as it conveyed by any drive system. The key pointfor providing optimized PV-type air-cushion with respect to flatnessaccuracy is to guarantee as much as deeded AD-stiffness with respect tospecific requirements for flatness, and to provide it by using as lessas possible MFR. According to different considerations, higher stiffnessthat can provides uniform and accurate ε_(n) can replace demandingmanufacturing tolerances for the platform. Typical values for thePV-type air-cushion stiffness are in the range of 3-60 gram/cm²/μm, andif thin objects like wafers or FPDs are supported or conveyed, a returnforces of local nature that are 10 to 200 times greater than the objectdistributed bodyweight, are developed in a vertical translation (up ordown) of only 1 μm.

The dependence of the AD-stiffness with ε, with respect to a specificaero-mechanic design of a PV-type air-cushion is characterized by anoptimum that is designed to be at the ε_(n). Accordingly, theAD-stiffness decays both at wider and narrower gaps. In particular, whenclosing the gap, the AD-stiffness vanishes before the gap is totallyclosed thus additional movements toward the active surface will notresult in increase of the fluidic return forces. It is important toidentify such behavior, to reduce the risk of contact that can be alsoof local nature and to guarantee no-contact in critical cases, where theobject is subjected to external forces, including forces that areassociated with accelerated motion of the gripped object, or in caseswhere the object is instantly subjected to additional weight, caseswhere a transitional process from one equilibrium state to anotheroccurs. Furthermore, the object may also be subjected to localenforcement where only a restricted zone is disturbed, it is importantespecially when the object is thin and of wide dimensions andaccordingly flexible, where the transitional process can be ofthree-dimensional nature. Therefore, a well functioning and effectivePV-type platform must operate at optimal conditions to provide highperformances of local nature.

When it is required to support or to convey without contact flat andthin low-weight objects, such as wafers or FPDs, at extremely highflatness accuracy, the inherently local-balanced PV-type air-cushion issuited for the task. Such low-weight flat and thin objects can be alsoflexible to some extent (with respect to their large lateraldimensions), typically have a distributed bodyweight of about 0.3gram/cm². and In case of supporting printing media the bodyweight can bemuch smaller. For example, when the active-surface platform is perfectlyflat and when applying high performance PV-type air-cushion, it ispossible to support with no-contact a 300 mm (in diameter) wafer with anoverall flatness accuracy of less than 1 μm, hovering at ε_(n)=20 μm.When using wide-format (50×180 cm) PV-type platform, it is veryexpensive to provide perfect manufacturing flatness for theactive-surface PV-type platform, to be optionally used to support inrest or to convey wide-format object, such as FPDs, during variousproduction stations. It is feasible to reach an overall operationalflatness of 10-50 μm, where half of it or less is contributed by theair-cushion itself. Furthermore, in many cases, the manufacturingprocess or quality control inspection of FPDs or wafers are performedalong a thin line, thus flatness is essentially needed only along thisline that is orthogonal to the direction of motion. It can be a linearmotion for FPD and rotational motion for wafers. When accurate flatnessis practically needed in a one-dimensional aspect, it is preferable,with respect to a preferred embodiment of the present invention to spendmuch effort in a close restricted area along the “process line” toimprove the flatness accuracy. It can be done by providing more inputpressure and/or by reducing the basic-cell dimensions close to the“process line”. Such passive means to improve locally the PV-typeair-cushion performances with respect to flatness accuracy, can beobtained only by mechanical setup, such as to provide different pressureand vacuum manifolds for the elongated accurate-zone and/or by changingthe flow-restrictors type, and/or by changing locally the resolution,etc. It is straightforward that high flatness performance may be neededalso in a restricted small zone of two-dimensional character(rectangular or round zone). In such cases, high performance can beprovided in restricted zone by adopting similar measures that are takento locally improve performances at the “process-line” case.

According to another preferred embodiment of the present invention, itis suggested to provide setting-screws along the “process-line” toregulate locally the flatness of the active-surface of the PV-typeplatform. Furthermore, according to another preferred embodiment of thepresent invention, it is suggested to create a separate pressure/vacuummanifolds to provide different conditions at the “process-line” of theplatform, and in addition to divide the manifolds into several sectionswhere at each of the sub-manifolds, a slightly different pressure (orvacuum) will be set in order to provide by purely aerodynamic means acompensation technique for improving the flatness along the processline. In such a technique, when an object such as FPD, is floatinghigher than allowed in a restricted zone along the “process line”, morevacuum or less pressure with respect to the nominal values will beadjusted and as a result, the object will be pulled down at thisrestricted zone in order to be gripped within the allowed tolerance, andif, on the contrary, such an object is floating lower than allowed inother restricted zone along the “process line”, less vacuum or morepressure with respect to the nominal values will be applied and as aresult, the object will be pushed up at this restricted zone in order tobe gripped within the allowed tolerance. Such an active flatnessadjustment mechanism can compensate also offset of manufacturingtolerances, It can be done at any time, particularly just after theplatform is assembled at the manufacturing site, and occasionally duringroutine service operations. The flatness adjustment may be also donewith respect to the process machine active component that also may benot flat, or it may move not accurately. In such a case it is possibleto compensate also this non-flatness and provide extremely high accuracyit terms of parallelism. This aerodynamic compensation technique can bealso implemented in a two-dimensional regional manner if needed.

In common cases, objects such as wafers, FPDs and inner PCB layers, arethin and flexible with respect to their lateral large dimension (wafers'typical thickness is 0.7 mm having a diameter of up to 300 mm, and FPDstypical thickness is 0.5 mm having a length of up to 200 cm). When Aprocess takes place, while such objects are gripped and remain at restor conveyed by the PV-type platform, an homogenous support of localbalance nature must be provided in order to avoid large scaledeformations and to keep the required flatness accuracy within theallowed tolerance. As mentioned before, the PV-type air cushion exhibitsinherently a “local balance” nature. It is common that such large andthin objects are not perfectly flat. In such cases, the PV-type aircushion provides another important feature: it has the ability to gripand to flatten with no-contact non-flat thin objects. The potential toflatten non-flat objects depends on the elasticity of the objects, butin the cases of the objects mentioned above, it is feasible to flattensuch thin objects that have non-flatness tolerances similar in scale tothe PV-type air-cushion gap. The non-contact mechanism of flattening bythe PV-type platform becomes available due to the presence of opposingforces that allow the production of pure flattening moments of localnature (see more details about flattening by pure moments when itdiscussed with respect to the PP-type platform). Although the PP-typeplatform to be discussed hereafter provides much more flatteningperformance, the PV-type is a one-sided non-contact platform and whenhigh accuracy is required, and only small non-flatness is allowed, thePV-type air-cushion support can provide adequate flattening mechanism toimprove the overall flatness accuracy of the non-contact PV-typeplatform.

In order to improve the flattening performance, an alternatingarrangement by rows can be applied where the pressure flow-restrictors,preferably SASO nozzles, are placed along one set of parallel lines andthe vacuum conduits, optionally equipped with low AD-resistanceflow-restrictors, such as another set of different SASO nozzles, areplaced along a second set of parallel lines, lapped equally in betweenthe pressure flow-restrictors set of lines on the platformactive-surface. With respect to another preferred embodiment of thepresent invention, it is an option to connect the conduits outlets ofeach of the lines (both for the pressure lines and the vacuum lines) bysurface grooves to improve the flattening performances. Thisline-PV-type air-cushion of one-dimensional format provides non-contactplatform with better a flattening performance in lateral direction,which is substantially not perpendicular to the lines, and with optimumperformance in a direction that is parallel to the flow-restrictorslines. It has to be mentioned that the flattening mechanism is of localnature, self adaptive and dynamic.

There are many different options to apply the inherently local-balancedPV-air cushion, with respect to preferred embodiments of the presentinvention, distinction has already been made between (a1) a PV-typeair-cushion that equipped with vacuum flow-restrictors when it isintended to stationary support or to convey objects when theactive-surface is not fully covered for at least part of the time, and(a2) a case where it is beneficial (more stiffness, lower manufacturingcost), not to use vacuum flow-restrictors when the active-surface of theplatform is fully covers. Another distinction made between (b1) a(common) case of supporting a horizontal object from its bottom side,(b2) a case of gripping a horizontal object with no contact from itsupper side, and (b3) holding objects that are vertically oriented or notoriented at all with respect to gravity.

Further distinctions made between (c1) the possibility of usingdifferent aspect-ratios for the basic cell of the PV-air-cushion, toenhance performances at the edges of the active-area, and here it isextended also to (c2) any practical arrangement of basic cells that canbe also non-repeatable in a spatial manner. It includes practicalarrangements on the active area where the number of pressure conduitsprovided is different from the number of vacuum conduits. It is alsopossible to apply the vacuum preloading PV-type air-cushion in acircular format where the vacuum and the pressure outlets aredistributed in a circular plan of a cylindrical coordinate system.Circular distribution is practical in cases where the active-surface ofthe PV-type platform is round and of relatively small dimensions.

Although we considered only flat surfaces so far, there is norestriction to create any practical active surface that is not flat. Atypical example is to shape a spherical active surface in order to gripspherical optical component, or a “V” shaped elongated active area toprovide a conveying line where a carriage with similar “V” shape bottomsurface can move in one horizontal direction with no lateral orrotational motion on top of such PV-type “slider” and secure thevertical direction. In fact, any practical side active surfaces can beimplemented when the object is supported from its bottom side oralternatively, when the PV-type air-cushion is applied upside-down. Inaddition separated “side” active-surfaces can be applied to limitlateral or rotational movements with no-contact.

When accuracy is not a major concern, it is possible, with respect toanother preferred embodiment of the present invention, to divide theactive surface of the PV-type platform in a one-dimensional manner intoseveral separated elongated active-surfaces at a lateral width of one orfew “basic cells” dimensions, to reduce costs, MFR and platformbodyweight, or alternatively, it is also possible, for the same reasons,to divide the active surface in a two-dimensional manner into severalseparated rectangular or round sub-surfaces. When dividing a supportingplatform, attention must be made to the risk of contact between theobject, which may be flexible, and the edges of the sub-surfaces due togravity, thus it must be done with respect to the elasticity of theanticipated levitated object. In the case of upper gripping, this riskdoes not exist, but a risk of disconnecting due to large downwardsdeformations at the areas between the sub-surfaces must be avoided, inorder to provide a secured non-contact upper gripping and conveying.

With respect to the preferred operational conditions of the presentinvention, the PV-type air cushion at (d1) an even equilibrium asalready presented, where the pressure level P_(ac) is almost equal tothe vacuum level V_(ac) and the area occupied by the pressure is almostequal to the area occupied by the vacuum, and both are similarlydistributed. Here it is extended also to additional two equilibriumstates: (d2) an operational condition where the pressure level P_(ac) ismuch larger (practically up to a factor of 2), than the vacuum levelV_(ac), and thus the area occupied by the pressure is much smaller thanthe area occupied by the vacuum, and both may not be similarlydistributed, (d3) an operational condition where the vacuum level V_(ac)is much larger (practically up to a factor of 2) than the pressure levelP_(ac) and thus the area occupied by the vacuum is smaller than the areaoccupied by the pressure and both may not similarly distributed. Theseunequal operational condition can beneficently be applied with respectto specific applications. for example, using more pressure to avoidlocal contacts when the object is supported at rest, or conveyed andsubjected to top-surface forces that may be connected to themanufacturing process, or use more vacuum to secures the non-contactgripping of objects from the upper side.

Although the PV-type platform can provide accurate support, and it mayalso be used in cases where accuracy is not essential, and safenon-contact gripping of local is the essential requirements. It isrelevant for many applications of the present invention such as (1)supporting or conveying with no-contact flat objects, such as FPD fromits upper side, where the main concern is to secure the object fromfalling down, (2) securing non-contact gripping of handling tools forflat objects, such as wafers or FPDs, where accelerated motion isinvolved, (3) supporting or conveying with no-contact flat objects, suchas wafers or FPDs, during the alignment or cleaning processes, (4) usinglimited size PV-type air-cushion at the top of landing pins to providenon-contact landing mechanism during the loading and the unloadingsequences of flat objects such as wafers, FPDs or PCBs.

When it is needed to convey at extremely accurate flat thin and wideformat objects such as FPD (typical current dimensions are up to 180×200cm), and the flatness accuracy is limited to a small zone, or to anelongated narrow zone, where the process takes place, the non-contactplatform incorporates PV-type with PA-type air-cushions in order toprovide cost-effective non-contact platform, where (a) In case ofelongated processing zone, such as coating or inspection, where theobject is transferred linearly during the process in a lateral directionnormal to the elongated processing zone, a PV-type air-cushion is usedto provide local high performance and flatness accuracy at an area thatis close to the elongated processing zone, but with marginal area toprovide relaxation of disturbances induced by outer zone, and when theε_(n) of the two types of air-cushion is not the same, but at the muchlarger outer supporting areas, before and after the elongated processingzone, a low cost PA-type air-cushion is used in places where the loadingand unloading sequences may be done. Similarly, such a division is alsopractical In case where (b) high flatness accuracy is desired at arestricted small processing zone, such as found in the step-by-stepphotolithography process, where an X-Y drive system is used to move veryaccurately around the objects (FPDs or wafers) from one step to theother. In that case PV-type air-cushion is used only at the smallprocessing zone. It is impotent to emphasize that a significantly widerrelaxation zone must be provided, much larger than the PV-typeair-cushion basic-cell typical scale, in order to provide a relaxationlength of several basic cell typical dimension (practically 4-10 cells)from all relevant sides. It is necessary in order to create an Isolationfrom outer-zones disturbances and smooth cross-area transfer, thusaccurate performance at the processing zone is obtained.

It is an option, with respect to another embodiment of the presentinvention to apply aerodynamic technique to adjust ε_(n), at theprocess-zone by regulating (such as modulating) the supply vacuum orpressure, or additionally, to create several distinct supplies at theprocessing zone to provide aerodynamic technique for local regulation ofthe vacuum or pressure supplies, in order to enhance locally theflatness accuracy at the processing zone.

In particular, when a process is taking place on the object whileconveying it at high flatness accuracy by a PV-type platform, theactive-surface can be divided into two or more sections to assist theprocess from its bottom side. Practically, a space may be providedbetween two sections, which for many applications discussed hereinabovemay be as wide as 10-50 mm in the direction of motion, without ruiningmuch of the high flatness of the gripped object, depending on theelasticity of the object. With respect to a preferred embodiment go thepresent invention, such an inter-section space can be useful in thefollowing manners: (1) It becomes possible to assist the process fromits bottom side as the process takes place above the object while it isconveyed without contact (continuously or at a step-by-step motion). Anysource of light for illumination or imaging, laser beams of low to highpower, as well as heating by radiation, or by hot air flow are only afew practical examples that become thus available. (2) It becomespossible to perform a dual-side process on both the upper and the lowersurfaces of the object, while it is accurately gripped above thenon-contact platform.

With respect to a preferred embodiment of the present invention, it ispossible to create a system based on the PV-type air-cushion where theobject is supported or conveyed with no contact, part of the time, butat the rest of the time it becomes a vacuum-table to hold down theobject in-contact for any practical reasons. Such a system can grip withor without contact objects that are much smaller than the platformactive-surface due to the AD-blockage mechanism of flow-restrictors thateffectively limit the waste of MFR at the uncovered areas in bothoperational cases. It can be done by turning off the pressure supply tothe active-surface where the object softly lands, where suchflow-restrictors, limit the flow. In similar way, when the pressuresupply is regenerated, the object disconnects and lifts softly. Withrespect to another application of the present invention, such a softprocess can be applied in vacuum table systems equipped with only onetype of flow-restrictors such as SASO-nozzles, where a soft non-contactlanding and disconnecting mechanism is applied. It can be done byfirstly operating with pressure, at the loading sequence, gentlyswitching to vacuum to provide soft landing, executing the process whilethe object is held down in contact by the vacuum, and finally switchingback to pressure to provide softly disconnecting and lifting process atthe unloading phase. The on/off switching of the pressure can be a rapidprocess when applying the low-volume integrated dual-manifold to bedescribed hereafter.

It is another preferred embodiment of the present invention, to engagetwo opposing active-surfaces, in one PV-type platform, havingsubstantially identical active-surfaces and aligned in parallel at amirror-image symmetry. Such a configuration provides dual-sidenon-contact gripping of an object that is inserted parallel in betweenthe opposing active-surfaces. The AD-stiffness of such a configurationis doubled and it is one of the most important features of suchnon-contact platform. The gaps between the two opposing air-cushionsshare the difference between the object width and the distance betweenthe opposing active-surface in a self adaptive manner. If the twoactive-surfaces are similar and operate at the same operationalconditions, the ε_(n) will be equal on either sides of the object. Infact, it is a similar configuration to the PP-type platform to bediscussed hereafter and it is also relevant to the dual-side PV-typeplatform. A significant disadvantage of the dual-side PV-type platformwith respect to the PP-type platform is the need to supply also vacuumand the potential to provide high AD-stiffness that is smaller, butthere is one significant advantage: the PV-type air-cushions do notapply large forces on the structure of the platform as the PP-typeair-cushions do.

Vacuum preload PV-type air-cushion can also be used as an alternativenon-contact air-bearing technology. (see the relevant paragraph withrespect to the PA-type air-cushion, but the main difference is theability of the PV-type air-cushion to exert holding-down forces tosecure the horizontal up-wise motion).

Pressure-Preloading (PP) Type Air-Cushion

According to a preferred embodiment of the present invention, PP-typeair-cushion is generated using an active surface with a plurality ofpressure ports, and another opposite active surface with a plurality ofpressure ports, each active surface generating forces that are oppositein direction with respect to the forces of the other active-surface.

Consequently, PP-type air-cushion is a pressure preloaded platform,where the object is supported at rest or conveyed with no-contact fromboth its sides, thus PP-type non-contact platform is unconditionallystable. The opposing active-surfaces of the PP-type platform arepreferably identical, provided with a plurality of pressureflow-restrictors such as SASO nozzles, and typically, with much lessnumber of evacuation holes, to create a well functioning FRS mechanismand accordingly achieve high performance. The two opposingactive-surfaces of the PP-type platform are assembled substantially inparallel, having identical active-surfaces and aligned in parallel witha mirror-image symmetry. The plane of symmetry is essentially theimaginary mid-plane of the thin (sectionally) and wide (laterally) spacethat is created between the two confronting active-surface. The twoopposing air-cushions are established as the object is inserted betweenthe two opposing active-surfaces. The gaps of the two opposingair-cushions share the difference between the object width and thedistance between the opposing active-surface in a self adaptive manner.If the two active-surfaces are similar and operate at the sameoperational conditions, the ε_(n) at both air-cushions will be equal.The distance between the two opposing surface must be adjusted to beequal to the anticipated supported object's width plus twice the desiredgap ε_(n). Accordingly, When It is intended to grip objects of differentwidth, the PP-type non-contact platform must includes a “panel widthadjustment” mechanis, allowing adjustment of the distance between thetwo opposing active-surfaces.

Due to pressure-preloading, PP-type platform provide high values ofAD-stuffiness compared with both PV-type and PA-type air-cushions. TheAD-stiffness of the dual-sided PP-type platform is of bi-directionalnature and does not depend on the object weight. Typically, thesupported objects, such as glass FPDs, wafers and PCB, are flat and haveparallel opposing surfaces. When such objects are not flat, the PP-typeplatform provides high flattening performance of self-adaptive nature.

The PP-type air-cushion includes two types of conduits, pressureconduits equipped with a flow-restrictors such as SASO-nozzles to caterfor the FRS behavior and evacuation holes, both preferably arranged in arectangular format (see FIG. 6 a) at the two opposing active-surface ofthe platform. The number of pressure flow-restrictors 22 that aredistributed over each of the active-surface is much larger with respectto the number of evacuation holes 24, which optionally may not beprovided at all (although it is recommended to provide evacuationholes), where factor of 3-16 may be practical (a factor of 9 is shown inthe basic cell 26 depicted in FIG. 6 a). Evacuation is needed to provideuniform camping and AD-stiffness of local nature, by providingevacuation holes and/or grooves at each of the opposing active-surfaces,mostly in cases where wide format active-surfaces are involved, orthrough the edges of these surfaces, mostly in cases where theactive-surfaces are definitely not wide (typically of width of one or afew basic-cells of that platform that shown in FIG. 6 a).

The PP-type platform may be described analogously by an electric-circuithaving two parallel conducing channels as shown in FIG. 5, where thenotations “up” and “dn” (down) are used to distinguish between the twoopposing active-surfaces. The text herein refers to a specific “channel”only when needed. R_(noz) represents the FRS flow-restrictors of thepressure conduits, which are preferably SASO-nozzles, and R_(ac)symbolized the AD-resistance of the opposing air-cushions. P_(in) is thesupply pressure, where it is an option to supply different pressures toeach of the opposing active-surfaces, and P_(ac) is the pressureintroduced to the air-cushions. ΔP is the pressure drop along theflow-restrictor R_(noz). P_(amb) is the outlet pressure that can beatmospheric pressure, or vacuum when vacuum preloading is in-additionapplied. MFR is the mass flow rate. R_(ac) is a flow-restrictor thatdepends on the air-cushion detailed design, and it include parameterssuch as the flow-restrictor resolution, the diameter of the conduit'soutlet and the ratio between the numbers of pressure outlet andevacuation-holes. At equilibrium state, R_(ac) depends on the ε_(n),which is essentially identical for both opposing air-cushions, butR_(ac) is a dynamic flow-restrictor where the AD-resistance depends in aself-adaptive manner with ε. When an offset of Δε from equilibrium isoccurs, the gap ε1 of the upper air-cushion becomes smaller ε1=ε_(n)−Δεand accordingly, the gap ε2 of the lower opposing air-cushion becomeslarger ε2=ε_(n)+Δε. In such an offset, the global force down ΣF_(p)^(UP) that applied on the object from it upper side are significantlylarger, and the opposing global forces up ΣF_(p) ^(dn) that applied onthe object from it lower side are significantly smaller, with respect tothe equilibrium state. Accordingly R_(ac) are dynamic resistorscharacterized by AD-resistance that is depends on the ε_(n) of bothsides. When the air-cushion is established, the pressure levelsintroduced to the opposing air-cushions are controlled by that gapoffset Δε.

The functionally of the PP-type air cushion may be disassociated withgravity. In equilibrium state, the object is supported by two opposingair-cushions at a substantially the same distance to the object, whichis symmetrically gripped in the middle of the platform, where the globalpressure forces ΣF_(p) ^(up) and ΣF_(p) ^(dn) that oppose each other areof the same order of magnitude. Both opposing forces may besubstantially larger in magnitude from the object weight, and thedifference between those opposing forces balances the gravity (dependingon the orientation of the system with respect to gravity). In such amagnitudes, the performances of the PP-type air-cushion with respect tothe AD-stiffness and accordingly to the flatness accuracy aredisassociated form the object weight. The PP-type air-cushion grips theobject with no-contact from both sides and accordingly it has aninherently bi-directional stiffness, which is a most important propertyof the PP-type air-cushion. It means that when trying to move the objecttowards one of the active-surfaces of the non-contact platform, opposingAD-forces are developed by the air-cushion in a self adaptive manner.With respect to a preferred embodiment of the present invention, (a) ahorizontal object can be gripped form both sides by a non-contactPP-type platform where the difference between the two opposing forcesbalances the object weight, or (b) a non-contact PP-type platform iscapable of gripping an object where the object facing-surfaces are nothorizontally oriented or even vertically oriented with respect togravity.

The dual-sided PP-type platform is of complex configuration as it hastwo active-surfaces, and the cost per area is at least doubled (withrespect to PA or PV platforms), if structural rigidity and complexity donot affect the system price. Therefore, it is worth considering only forspecific tasks. Indeed, with respect to the present invention, thenon-contact PP-type platforms are of superior performance having theability to flatten non-flat objects, and at the same time to providehigh accuracy when the object is gripped at rest or while conveyedwithout contact. Therefore, high flattening performance is the mostimportant feature of the PP-type platform.

The PP-type platform provides a flattening mechanism of local nature,where when the object is not flat, pure flattening moments are developedin a self-adaptive manner by re-distribution of ε in such a way that εbecomes ε(x,y) and the off-set Δε(x,y) must be of both negative andpositive signs in order to provide both pure flattening moments and newoff-set equilibrium state, to balances the object weight. Furthermore,the self-adaptive flattening nature of the PP-type platform is also timedependent in cases where a non-flat object is conveyed by the platformwith non-flatness NF(x′,y′) with respect to a moving coordinate systemthat is attached to the traveling object (x′,y′). In such a dynamiccase, the offset as becomes of three-dimensional character Δε(x,y,t).Nevertheless, the self-adaptive flattening mechanism exhibits temporaland local nature. For specific requirements of flattening performancewith respect to the object's elasticity, width and lateral dimensioned,the larger the AD-stiffness of the PP-type platform is, the smaller isthe Δε(x,y), Therefore. high AD-stiffness is needed to provide anon-contact platform with high performances in terms of flattening andflatness-accuracy.

In order to understand the pressure preloading mechanism associated withthe PP-type platform, we shell refer to a case where a thin and flatobject is horizontally supported or conveyed. In order to establish thedual-side air-cushions, the whole object or part of it must be insertedbetween the two opposing active-surfaces of the platform. Where theactive-area will be only the area on the active-surface of the platformwhere the object subsists. In equilibrium state, the upper and the lowerair-cushions induce opposing forces on the object, and the resultant ofthese forces balances gravity. Since the active-surfaces of the PP-typeplatform are identical and aligned in a “mirror-image” symmetry withrespect to the central plane of the platform, the pressure distributionson both sides of the object are almost identical, as illustrated in FIG.6 b, equilibrium case. The dynamic characteristics of the PP-typeplatform are hereby explained with reference to FIG. 6 b. When trying tounbalanced the PP-type air-cushion by offsetting it down by Δε (see FIG.6 b, offset down case), the gap of the upper air-cushion ε₁ is increasedand the gap of the lower air-cushion ε₂ is decreased. Accordingly, thepressure introduced to the lower air-cushion P_(ac) ^(dn) significantlyincreases as portion of ΔP^(dn) is released by the FRS flow-restrictorsR_(ac) ^(dn), as the MFR^(dn) of the lower air-cushion is reduced whenthe AD-resistance of the lower air-cushion R_(ac) ^(dn) increases. As aresult, a global lifting force ΣF_(p) ^(dn) is exerted on the object bythe lower air-cushion that significantly increases by additional forceΔΣF_(p) ^(dn). Simultaneously the pressure introduced to the upperair-cushion P_(ac) ^(up) significantly decreases as ΔP^(up) insideflow-restrictors R_(ac) ^(up) (of similar characteristics with respectto R_(ac) ^(dn)), increases as the MFR^(up) of the upper air-cushionintensifies when the AD-resistance of the upper air cushion R_(ac) ^(up)is decreased. As a result the counter direction (down) global forcesΣF_(p) ^(up), exerted on the object by the upper air-cushion aresignificantly decreased by ΔΣF_(p) ^(up). Accordingly, large opposingforces from both sides push the object up to equilibrium-state. In asame way, when trying to unbalanced the PP-type air-cushion byoffsetting it up by Δε (see FIG. 6 b, offset up case), the gap of theupper air-cushion ε₁ decreases, and the gap of the lower sideair-cushion ε₂ increases as a result of similar occurrences. But in thecounter direction, large opposing global forces ΣF_(p) ^(dn) push theobject down to equilibrium-state.

Some conclusions stem from the above explanation. Firstly, thebi-directional inherent characteristic of the PP-air-cushion is clearlyevident. Secondly, it sheds a light on the meaning of the term “pressurepreloading”; When the forces ΣF_(p) ^(up) and ΣF_(p) ^(dn) are muchlarger than the object weight (for example, 50-500 times higher), and anoffset by Δε in the range of 5%-10% with respect to ε_(n) occurs.ΔΣF_(p) ^(up) and ΔΣF_(p) ^(dn) are also much larger than the objectweight (20-200 times larger with respect to the above example).Accordingly ΔΣF_(p) ^(up) and ΔΣF_(p) ^(dn) are almost equal to theiraverage value ΔΣF_(p), because the two changes contribute FRS forces inboth cases where the offset is up or down. Accordingly, the “net” FRSforces that act on the object at offset of Δεfrom ε_(n) equals to twiceΔΣF_(p) and the essential meaning of the pressure-preloading mechanismis the fact that the FRS forces are doubled (with respect to a one-sidedair-cushion, as in the PA-air-cushion, that is preloaded by only theweight of the object). The higher the PFR forces are, with respect tosmall As offset, the higher the air-cushion AD-stiffness is. The PP-typeair-cushion may potentially generate AD-stiffness that is much largerwith respect to the PA-type or PV-type air-cushions.

High AD-stiffness performance of the PP-type platform can be obtained byimplementing the following considerations: (1) It is most important withrespect to the present invention to use of a plurality offlow-restrictors such as SASO nozzles, to introduce the flow to thePP-type air-cushion, these flow-restrictors serving as a FRS of localnature, and providing a self-adaptive mechanism that is rapidlygenerating opposing forces in response to any changes in ε (2)Optimization of the FRS mechanism can be obtained by adjusting theAD-resistance of the flow restrictors (R_(noz)), with respect to theair-cushion AD-resistance (R_(ac)) in such a way that when theair-cushion is working at a predetermined ε_(n), half of the inputpressure P_(in) is introduced to the air cushion (P_(ac)), thus theother half (ΔP), is used up as a potential pressure drop inside theflow-restrictor to serve the FRS mechanism when ε_(n) is off-setted byΔε. In such conditions, maximum AD-stiffness is obtained at the ε_(n)(3)

It is very important, with respect to PP-type platforms of the presentinvention, to maximize the effective area of the active-surface in ordernot to reduce the benefits of the pressure preloading mechanism. Withrespect to a preferred embodiment of the present invention, it can bedone by distributing much more flow-restrictors than evacuation holes,where a factor of 9 that is shown in FIG. 6 a seems to a convenientfactor. Practical factors are, for many purposes, in the range of 3-16.It has to be emphasized that the evacuation holes are used to provideuniform and high stiffness at internal zones of the active-area of thePP-type air-cushion, and to maintain the local balance nature.Evacuation must be done in a way that avoids significant changes in thepressure distribution, changes that were found to be very effective inenhancing the AD-stiffness and the functionality of the PA-type andPV-type platforms, but significantly reduce the AD-stiffness of thePP-type platform. Other practical parameters enhancing the AD-stiffnessinclude (4) working at high operational pressure, where the more theinput pressure and thus the more MFR, the more AD-stiffness isintensified. (5) If there are no system or process restrictions, it ispreferable to reduce the predetermined equilibrium gap ε_(n) to gainmore sensitivity to offsets Δε, and it means high AD-stiffness atpossibly lower MFR.

Enhanced FRS forces can be obtained by using also vacuum preloading,where the payoff is reduced values of ΣF_(p) ^(up) and ΔΣF_(p) ^(dn). Itis acceptable if the main objective is to enhance AD-stiffness.Therefore, with respect to another preferred embodiment of the presentinvention, it is an option to connect the evacuation holes to vacuumsource, thus, in addition to the basic pressure preloading character ofthe PP-type platform, vacuum preloading mechanism may additionally beimplemented in order to further enhanced the AD-stiffness of thisplatform.

Pressure and vacuum preloading are very known mechanisms to enhancedAD-stiffness and are frequently used in air-bearings application toprovide accurate motion-systems. However, with respect to the specificapplication of the present invention, when applying preload mechanisms,in particular pressure preloading, for the PP-type platform and whenaimed at providing non-contact gripping and flattening mechanism ofessentially thin and wide flat-objects while supported at rest orconveyed by motion-system, this is basically a new platform of differentembodiment and its functionally and objectives are totally differentfrom air-bearing applications. Also different are the operationalconditions. The PP-type air-cushion may also be operated at pressuresupply that is much more than one Bar above the atmospheric pressure,and in most cases a few hundreds of millibars, specifically, for manypruposes, the range between 100-1000 millibars, which are very practicaloperational values, the active area of the PP-type air-cushion beingvery large with respect to the active-area of air-bearing systems. Inaddition, a typical air-gap of air-bearing systems is in the range of3-10 μm, while the typical gap (ε_(n)) of the two opposing air-cushionsof the PP-type platform is effective in the range of 10-1000 μm. ThePP-type platform air-cushion gap, ε_(n), is selected with chosen to meetthe required accuracy and flattening performances needed with respect tothe object elasticity, its width and lateral dimensions.

With respect to another preferred embodiment of the present invention,the PP-type platform, which has a wide active-surface and works atconvenient operational conditions, can be implemented to linear motionsystems as a replacement to the air-bearing motion-systems. The lattershave a much smaller active-area and work at severe operationalconditions (with respect to operational pressure and floating gap thatdictates a very smooth sliding surface). Thus it is possible to provide,employing a system in acordnace with the present invention, similarAD-stiffness and accurate linear motion. When adopting the PP-typePlatform for routine air-bearing applications, it can be in aconfiguration where it is implemented on a traveling carriage havingactive opposing surfaces that slide along a special passive slider,gripping the object from both sides thus avoiding vertical movements, oron the opposite, it can be configured as a passive carriage, that isvertically gripped, and travels over a sliding rail, which has activeopposing surfaces. The latter configuration is feasible only when MFR isof no concern. Indeed, the use of reduced operational pressure, and thebeneficial use of the AD blockage mechanism provided by the plurality offlow-restrictors, which limit the MFR at the uncovered areas, makes thisconfiguration practical. With respect to preferred embodiments of thepresent invention, The PP-type air-cushion can be employed, (1) with orwithout respect to the direction of gravity, (2) in linear motionsystems of different configurations such as (2a) one-directional linearmotion systems, (2b) two-axes planner motion systems, and (2c) systemswhere rotational motion is involved, such as spindles and rotary tables.

The PP-type air-cushion performance exhibits local-balance nature thusno-global effect occurs. Therefore it is possible to provide much aswide as needed non-contact PP-type platform to support or to convey flatobjects of extremely large dimensions, such as glass plates, FPDs orPCB. It has to be emphasized that the locality and uniformity nature isvalid as long as the dimensions of the basic-cell of the PP-typeplatform are much smaller with respect to object lateral dimensions.Locality and uniformity are no-longer valid at areas that are close tothe edges of the active-areas. In order to encounter the edge effects itis recommended to increase the resolution close to the edges of theactive-area and optionally even not to provide evacuation holes inclosed to the edges of the active-areas, where evacuation is availableover the edges, thus reducing the lateral scale of the edge effects. Forthe same purpose it is also an option to differentiate the pressuresupply and provide higher pressure to edge-areas. Such edge-treatmentimproves the edge-areas performances.

Typically, with respect to a preferred operational condition of thepresent invention, as a flat object is of large dimensions or whenmoderate performance is desired, wider ε_(n), lower operational pressureand preferably larger basic-cell dimensions (less resolution) can beapplied, and as the object is of small dimensions or it is more elasticand when high AD-flatness is needed to provide high performance in termsof flattening capabilities and flatness-accuracy, narrower ε_(n), higheroperational pressure and smaller basic-cell dimensions (more resolution)are preferred. For many purposes, the practical dimensions of the basiccell, which contains 9 squares as shown in FIG. 6 a, are between 15×15mm to 72×72 mm. It is also an option that the two lateral dimensions ofthe basic cell may not be of the same lengths. It is very practical touse different aspect ratio for the basic cells when these are close tothe edges of the active-area, and to provide fine resolution in thedirection that is normal to that edges, to improve local performance atthe edges of the non-contact platform.

The aero-mechanic design of the PP-type non-contact dual-side platformmust be pedantically performed, taking into account (1) The operationalconditions and the available MFR. (2) The characteristics of theflow-restrictors (in terms of MFR vs. the input and the outputpressure). In particular, with respect to the present invention, it ispreferred to use SASO-nozzles as the FRS flow-restrictors. (3)Geometrical parameters such as the lateral dimensions of basic cell (inother words: the resolution of the platform), as well as the factorbetween the number of flow-resistors and the evacuation-holes, where apreferable and a convenient value of that factor is in the range of3-16, and the details of the outlets of both the pressure conduits theevacuation holes. Typical values of AD-stiffness for the PP-typeplatform are in the range of 10-200 gram/cm²/μm, and if thin objectslike wafers or FPDS are supported in rest or conveyed, a FRS force,which is 50 to 1000 times greater than the object weight, may bedeveloped with respect to a As of only 1 μm.

The nature of the AD-stiffness at different floating gap, with respectto a specific aero-mechanic design of a PP-type platform, ischaracterized by an optimum equilibrium gap ε_(n). Accordingly, theAD-stiffness decays both at wider and narrower gaps. It is important toidentify such behavior, to guarantee well functioning and no-contactthat can be also of local nature, in cases where the object is subjectedto external forces, including forces that are related to acceleratedmotion, or in cases where the object is instantly subjected to externalforces. Such enforcements on the object may occurs also in a localmanner where only a restricted zone is disturbed, Furthermore, it ismostly important to guarantee no-contact especially when the object isthin and of wide dimensions and accordingly flexible, where local forcesmay produce deformations of three-dimensional nature.

When it is required to support at rest or to convey with no-contact flatand thin low-weight objects of wide dimensions such as wafers, FPDs orPCBs (inner and outer layers), at extremely high flatness accuracy, thelocal-balanced PP-type platform is suited to be selected to perform thetask. Furthermore, the PP-type platform has a capability to provide highflattening performance, which is very effective in cases where theobject is not flat and still high flatness accuracy is necessary at azone where accurate processing takes place. The PP-type platform canprovide, with respect to the elasticity of the above mentioned objects,flatness accuracy in terms of a few micrometers at the processing zonewhere the object non-flatness is commonly measured in term of up to afew millimeters and more. With respect to a preferred configuration ofthe present invention, (1) the processing zone can be either anelongated zone opened between two sections of the PP-type platform, or(2) an internal rectangular or circular processing zone can be opened, azone that is much smaller than both the PV-type platform active surfaceand the object dimensions. When the conveyed object is both wide andlong, it is expensive to provide overall manufacturing flatness of theactive-surfaces and overall operational flatness accuracy that includeserrors that are contributed by the air-cushion itself and additionalerrors of the motion system and the gripping elements. Therefore it iscost-effective, with respect to a proffered embodiment of the presentinvention, to configure a non-contact platform where the PP-typeair-cushion is applied only at a section of the platform, to providehigh flatness performances only close to the zone where the accurateprocessing takes place, and elsewhere the PA-type air-cushion or anyother means of conveying may be used.

Although we considered only flat surfaces so far, there is norestriction to create, with respect to another preferred embodiment ofthe present invention, any practical active-surface that is not flat,for applications where high flatness-accuracy must be provided at theprocessing-zone. It is true also for PV-type and PA-type platforms,Typical example is to shape the two opposing active surfaces of thePP-type platform in a cylindrical shape where the diameter of thecylindrical surface can be large, thus reducing lateral wavy patterns.Such a surface can be very useful when flexible object such as found inthe printing world are considered, or even when FPDs or PCBs innerlayer, are considered, where a curvature in one-dimension significantlyincreases the rigidity of such flat, thin and flexible objects. Theopposing active-surfaces of the PP-type platform can also be “v” shapedfor linear motion application where a passive carriage is accuratelyslided over an active elongated PP-type platform (slider) andvise-versa. The latter and other similar configurations provide accuratemotion where lateral movements are prevented.

With respect to the operational conditions of PP-type platform, thehigher the input pressure is, the higher are the AD-stiffness andaccordingly the associated performance. But, with respect to flat, thinand wide objects such as wafers, FPDs or PCBs, effective operationalpressure is in the range of 100-1000 millibars. it has to be emphasizedthat very large forces may be develop if working with high pressure andwide active-surfaces. Such forces threaten to tear apart this dual-sideconfiguration thus it is suggested, with respect to another preferredembodiment of the present invention, to provide only as much as neededpressure supply and not more, and to limit the lateral size of theactive-surfaces and accordingly to design a strong structure for theplatform, otherwise the flatness-accuracy will deteriorate. For example:opposing forces of 1000 kg may be developed in a PP-type platform havingactive-area of 100×40 cm when working at pressure supply of 250millibars. The dual side PP-type platform must be very rigid to maintainthe ε_(n) within the allowed tolerance, and not to be affected bydynamic structural deformations. Practical ε_(n) for the PP-typeair-cushions is in the range of 20-500 micrometers. Also, when equaloperational conditions for the two opposing air cushion are considered,it is an option to design the PP-type platform to operate at differentoperational conditions and at different ε₁ and ε₂.

Accordingly, with respect to another preferred embodiment of the presentinvention, it is an option to connect the active-surfaces of theplatform by use of pre-loaded supporting mechanical springs in order tolimit the maximum forces that may be developed, thus when AD-forcessurpass beyond their limit, the opposing active surfaces are adjustedfurther apart, and the gap of the air-cushions widens in a self-adaptivemanner. Accordingly, a global “force-limit mechanism” is created. Theuse of such mechanical spring can be also helpful in cases where theobjects widths are not uniform and the machinery of thewidth-compensation sub-system that must be included in the PP-typeplatform if objects such as PCB or FPD of essentially different widthare occasionally considered, and such a sub-system is designed to adjustthe Air-cushion gaps only for a nominal object width.

The non-contact PP-type platform offers high performance in terms ofstiffness, flattening capacities and at-rest or in-motion flatnessaccuracy gripping, Accordingly, with respect to the present invention,it is preferred to use the PV-type platform when such high performancesare needed. But, the PP-type platform can be useful for other reasons,such as safety reason, hence from stability point of view, the PP-typeplatform is supeiorly stable. Furthermore, PP-type platform allowsdual-sided process to be carried. It may be relevant for flat objectssuch as FPDs wafers and PCBs, to be supported or conveyed withno-contact while any process activity is taking place on both its sides.Such objects may not be flat, and the high flattening capabilities, suchas the PP-type platform provides, are needed to meet the processflatness-accuracy requirements.

When it is needed to convey at extremely flatness-accurate thin and wideformat objects such as FPD (commonly, actual dimensions are up to180×200 cm), or PCB that are not flat in most cases and the flatnessaccuracy is desired for a small zone or for an elongated narrow zonewhere the process takes place, it is preferable and cost-effective touse PP-type air-cushion at the processing zone, with the PA-type or thePV-type air-cushions serving as a non-contact platform. As mentionedbefore, a relaxation length must be specified to avoid effects ofexternal disturbances. With respect to a preferred embodiment of thepresent invention, it can be implemented (1) In case of elongatedprocessing zone, such as cleaning, coating or inspection, where theobject is transferred linearly during the process in a direction that isnormal to the elongated processing zone. (2) Similarly, in the case ofwafers support, it is convenient that the elongated processing zone bethe radial direction where the object is rotated around its center.

With respect to another preferred embodiment of the present invention,it is suggested to (3) support and to flatten the object by a PP-typeair-cushion that is provided only at a restricted area close to theelongated processing zone, but wide enough to allow relaxation, and inthe much larger outer supporting areas, before and after the processingzone, a low cost PA-type or PV-type air-cushions may be provided, oralternatively, any other practical supporting means. (4) in cases whereonly a small, two-dimensional processing zone is reqiured (such as foundin the lithography process, where X-Y horizontal steppers are commonlyused to move objects such as FPD or wafers, step by step), it isconvenient to apply the PP-type air-cushion only at a restricted zonearound the small processing zone, where at the outer large areas aroundthe accurate zone, it is practical to employ the lower-cost PA-type orPV-type air-cushions. It has to be emphasized again that In both cases(3 and 4), it is suggested to provide a relaxation strech such asdescribed at the PV-type air-cushion.

In addition, with respect to a preferred embodiment of the presentinvention (5) It is an option to apply aerodynamic techniques toregulating the pressure at one of the active-surfaces of the dual-sidePP-type platform, in order to adjust the distance between the objectsurface and the process machine active element, possibly at each step,or constantly, by involving a control system. Furthermore (6) it is anoption to divide the actual processing zone into several sectors, toprovide also local adjustment of that distance. With respect to thisoption, It is convenient to divide the processing zone into severalindividually pressure-controlled sectors. It can be achieved either atthe factory or by on-line controls.

In particular, when processing takes place on the object while it isflattened and supported or conveyed with no contact at high flatnessaccuracy by the PP-type air-cushion, the upper and the loweractive-surfaces of that platform can be similarly divided into two ormore sections, to assist the processing from both sides of the object.In Particular, the space created between two sections can be as wide as10-50 mm in the direction of motion, without spoiling much the flatnessaccuracy of the gripped object, but it depends of course on theelasticity of the object. Such an inter-section space can be useful inthe following manners: (1) It allows room for reaching and performingthe processing from its upper side as the process takes place above theobject, while it is flattened and conveyed without contact at highflatness accuracy (continuously or at a step-by-step motion). Any sourceof light for illumination or imaging, laser beam of any power as well asheating by radiation or by hot air flow are only a few practicalexamples that become available. (2) It becomes possible to performdual-sided processing (possibly simultaneously), on both the upper andthe lower surfaces of the object, while it is flattened and accuratelygripped or conveyed inside the PP-type non-contact platform. Such adivided platform can grip with no-contact objects that are much smallerthan the active-area of the platform due to the AD blockage mechanism,which is provided by flow-restrictors.

The vacuum preload PP-type air-cushion can also be used as analternative to the non-contact air-bearing technology, especially incases where accurate-motion is required and the object is of moderate orlow weight, where it may be subjected to local and temporal externalforces, and where the pressure preloading provides high AD-stiffnessthat is disassociated from the object bodyweight.

When only one active-surface such as for the PP-type platform is placedagainst a thin object and a second non-active plate is positioned on theother side of the object, only one air-cushion presses the objectagainst the non-active surface. Such platforms is referred to herein asa PM-type air-cushion. The PM-type platform can be used with or withoutrespect to gravity. It can be used for many applications to flattenand/or to increase lateral friction forces on objects such as FPD, PCBwafers or any printing world media without touching the surface of theobject that is facing the air-cushion side, where touching this surfaceis forbidden. The surfaces of the PM-type platform can be planar ornon-planar, for example cylindrically shaped or V-shaped (or in anyother desired shape). The active-surface of the PM-type platform can bestationary while the non-active surface with the object may be inmotion, or vise-versa. It may include or combine linear motion androtating motion with a spinning direction that is perpendicular to thesurface or, when a cylinder is used as the non-active surface, it is anoption to revolve the cylinder. It has to be emphasized that the PM-typeplatform is used to apply forces in a cost-effective manner and theAD-stiffness is provided in a self-adaptive manner to the platform byusing pressure flow-restrictors such as SASO nozzles, with respect tonon-uniform objects and to provide a AD-blockage mechanism that limitsthe MFR when the active-surface of the platform is not fully covered(when the object is of smaller lateral dimensions). Accordingly, andsince flatness is mainly defined by the flatness of the non-activesurface of the platform, the AD detailed design of the PP-type platformis different from the the AD detailed design of the PP-type platformwith respect to evacuation holes and resolution, and high AD-stiffnessmay not be the top-priority performance.

According to a preferred embodiment of the present invention, eachactive surface of the non-contact support system is equipped with aplurality of pressure-flow restrictor to provide the FRS capabilitieswhich is the most important element of the present invention. Inpreferred embodiments of the present invention it is recommended to usethe SASO flow-restrictors described in WO 01/14782, WO 01/14752 and WO01/19572, all incorporated herein by reference. Generally, a SASOflow-restrictor (see FIG. 7) described therein comprises a conduit 70having generally two substantially opposite rows of fins 72, 74positioned inside the conduit, protruding internally, one row of finsshifted with respect to the other row, so that opposite the cavities 76,77 formed between consecutive fins of one row a fin of the other row ispositioned, to allow a formation of vortices within these cavities whenair (or other fluid) flows through the conduit, and the formation of athin core-flow 78, substantially confined between the tips of the fins.An elaborate description and explanation of the nature of the conduitand the nature of the flow within is found in the above mentionedpublications, the performance of the SASO flow-restrictor, the FRSmechanism and the AD-blockage mechanism of self-adaptive nature aredescribed hereinabove.

In accordance with a preferred embodiment of the present inventionreference is now made to FIG. 8 a, illustrating a PA-type non-contactplatform 80 a, having a flat active-surface 81, equipped basic cells ina chess-table format (to provide uniform support and local balance),with a plurality of pressure outlets equipped with flow-restrictors 82,preferably SASO nozzles, aimed at facilitating PRS characteristics ofplatform 80 a and securing the pressure level when the active-surface isnot fully covered, and a plurality of evacuation vents 83. It has to beemphasized that the resistor-symbol” denoted for the flow-restrictor asshown in the figures is used only as a symbolic illustrating, and theactual details of flow-restrictors 82, are shown for example in FIG. 7,and described in great details in WO 01/14782, WO 01/14752 and WO01/19572, all incorporated herein by reference. A PA-type air-cushion 85is established between the object's 500 lower surface and theactive-surface 81 when an object 500, that may be larger, substantiallyequal or much smaller than the active-surface 81, is placed in parallelin a close vicinity over the active-surface 81 of the platform 80 a (ata predetermined gap ε_(n)). The object 500 may optionally be at rest orconveyed or towed in a direction defined by the arrow 501. The outlets82 a of the pressure flow-restrictors 82, that introduce the air to theair-cushion 85, and the outlets 83 a of the evacuation vents 83 throughwhich the air is released from the air-cushion 85, are distributed atthe active-surface 81 in an alternating format. The diameters of outlets82 a, 83 a may vary, may be unequal and have a round shape or othershape. Each of the inlets of the pressure flow-restrictors 82 isfluidically connected to a pressure reservoir 86, itself fluidicallyconnected to an air-pump 86 a to provide pressurized air. Alternatively,each of the inlets of the pressure flow-restrictors 82 is fluidicallyconnected to an integrated single-manifold to be described hereafter(see FIG. 15 a), that is fluidically connected to an air-pump 86 a. Itis an option to provide a flow restrictor in the evacuation channel inorder to raise the average air-cushion pressure.

The performance of the PA-type non-contact platform can be determined byspecifying a variety of mechanical and aeromechanical means, including,(1) the dimensions of the platform with respect to the dimensions of theobject to be supported by the system. It may include allocation ofrelaxation areas to decay outside disturbances and vibrations (2) theflow-restrictors characteristics (and with respect to the preferredflow-restrictor, by specifying the geometric parameters of the SASOnozzle configuration and physical dimensions), (3) the air-cushion gapε_(n), (4) the PA-air-cushion basic-cell dimensions and details, and (5)the operational conditions. From application point of view, theaeromechanic design must take into account (6) flatness accuracy andother performance specifications (7) the character of the object(materials, bodyweight and dimensions), and (8) the details of themotion involved, and (9) the details of the processing involved,including dimensions and forces that be by developed.

Reference is now made to FIG. 8 b, illustrating a PA-type non-contactplatform 80 b in accordance with another preferred embodiment of thepresent invention, having a flat active-surface 81 with basic cells in achess-table format (to provide uniform support and local balance), witha plurality of pressure flow-restrictors 82. In addition here,surface-grooves 88 are provided at the active surface 81, in parallel tothe direction of motion 85, in order to assist the air-evacuation, wherethe air can be released to atmosphere at the end of the grooves or byoptional bores 88 b. Evacuation-grooves can be also made inperpendicular to the direction of motion 501. Alternatively, theevacuation vents 83 may be omitted and evacuation is achieved onlythrough the evacuation grooves.

Furthermore, In accordance with another preferred embodiment of thepresent invention, the flat active-surface 81 of the PA-type non-contactplatform 80 c can be divided to several elongated segments 89 along thedirection of motion 501 of the object, (a division into two segments isshown in FIG. 8 c). In this case the evacuation is partly performedthrough each of the elongated spaces 89 a provided between the segments89 (see right side). Alternatively, evacuation holes may not be usedthus evacuation is achieved solely through the elongated spaces 89 a(see left side). The active-surface 81 can be divided also inperpendicular to the direction of motion or in a two-dimensional manner.In general evacuation surface-grooves (not seen in this figure), mayalso be incorporated. In particular, such opened spaces can be used forhandling and conveying tools, to position sensors for motion or processcontrol, and access the object so as to allow processing that may takeplace above the object, optionally even performing a dual-sidedprocessing. The active surface may be provided with one or morethrough-openings for the purpose of handling operations on the object.

The active-surface of the PA-type non-contact platform in accordancewith the present invention is preferably planar, suited for manysupporting and conveying purposes, but it may also be cylindrical,curved or tortuous, according to specific design requirements, and thenature of objects supported or conveyed on it, and it may also depend onthe nature of processing to be optionally performed above it. Processingmay take place also at outer zones that are close to the edges of theactive-area. It has to be emphasized that the active-surface of thePA-Type is not always rectangular and it may be of any desired shape. Inparticular it is convenient to use round PA-type platform to support around wafer, which may be held at rest or moved in a turning motion.Although it is convenient to use a chess-table format for allocating theoutlets, the two lateral dimension of the basic cell (see FIG. 2 a)should not necessarily be equal. In particular, it is favorable to applyfine resolution close to the edges of the active-surfaces. In theembodiments depicted in the figures one evacuation hole (if at all) isassociated with each of the flow restrictors, but it is possible toselect any other ratio between them, in order to handle effectivelyultra-low-weight objects (for example, for the purpose of finger touchsupport more evacuation are needed) or heavy objects (where lessevacuation is needed in order to provide enough force to balancegravity).

In accordance with a preferred embodiment of the present inventionreference is now made to FIG. 9 a, illustrating the PV-type non-contactplatform 90 a having a flat active-surface 91, in a chess-table format(to provide uniform support and local balance), with a plurality ofpressure outlets with flow-restrictors 92, and a plurality ofvacuum-conduits 93. PV-type air-cushion 95 is established between theobject 500 lower surface and the active-surface 91 when an object 500,which fully covers the active-surface 91, and can be essentially equalor larger than active surface 91, is placed in parallel in a closevicinity to the active-surface 91 of the platform 90 a, (at apredetermined gap ε_(n)). The object is supported at rest, but mayoptionally be conveyed, however it must at least fully cover theactive-surface 91 (as frequently found in circular configurations suchas wafers, hard-disc, CD,DVD ex). The pressure outlets 92 a of thepressure flow-restrictors 92, which introduce the air to feed theair-cushion 95, and the vacuum outlets 53 a of the vacuum-conduits 93through which the air is sucked from the air-cushion 95, are distributedat the active-surface 91 in an alternating format. The outlets 92 a,93 aare not necessarily equal nor must have a round shape. Each of theinlets of the flow-restrictors 92 is fluidically connected to abottom-side pressure reservoir 96, that is fluidically connected to anair-pump 96 a providing pressurized air, and each of the inlets of thevacuum-conduits 93 is fluidically connected to a bottom-side vacuumreservoir 97, which is fluidically connected to a vacuum-pump 97 a toprovide vacuum suction. Alternatively, each of the inlets of theflow-restrictors 92 and the inlets of the vacuum conduits 93 isfluidically connected to a bottom-side integrated double-manifold to bedescribed hereafter (see FIG. 15 b), which is fluidically connected toan air-pump 96 a and a vacuum pump 97 a. It is an option to use one pumpto supply both pressure (to be connected to the pump-outlet) and vacuum(to be connected to the pump-inlet), but it may limit the performanceand the option of aerodynamic adjustments and is therefore notrecommended.

The performance of PV-type non-contact platform can be determined byspecifying a variety of mechanical and aeromechanical means, including,in addition to the dimensions of the platform, also (1) theflow-restrictors characteristics (and with respect to the preferredflow-restrictor, by specifying the geometric parameters of the SASOnozzle configuration and physical dimensions), (2) the air-cushion gapEn, (3) the PV-tape air-cushion basic-cell dimensions and details, and(4) the operational conditions, including optional means of regulationand control. It is a possibility to apply local vacuum/pressureregulation by dividing the active-surface or part of it to severalindividually regulated sectors to enhance flatness-accuracy. For thePV-type platform, one-dimensional sectors distribution is applicable atthe edges areas, which are close to the laterally wide and short spacewhere processing may take place, as shown in the divided configuration,see FIG. 9 c, or at the “Processing zone” if it takes place above theobject. From the application point of view, the aeromechanic designconsiderations must include the (5) flatness accuracy and otherperformance specifications (6) the character of the object (materialsaspects, bodyweight and dimensions), and (7) the details of the motioninvolved, and (8) the nature of the processing involved, includingdimensions and forces that need to be developed.

In accordance to another preferred embodiment of the present inventionreference is now made to FIG. 9 b, illustrating the PV-type non-contactplatform 90 b having a flat active-surface 91, equipped in a chess-tableformat (to provide a uniform support and local-balance), with aplurality of pressure flow-restrictors 92. preferably SASO nozzle, toprovide the PRS characteristics of platform 90 b, and a plurality ofvacuum flow-restrictors 94 of much lower AD-resistance with respect to92, preferably SASO nozzles. The PV-type air-cushion 95 is establishedbetween the object 500 lower surface and the active-surface 91 when anobject 500 that may be larger, essentially equal or much smaller thanthe active-surface 91, in parallel placed in a close vicinity to theactive-surface 91 of the platform 90 b (at a predetermined gap ε_(n)).The object 500 can optionally be supported at rest or be conveyed in adirection that is indicated by arrow 501. Both flow-restrictors 92, 94secure the vacuum and the pressure level when the active-surface 91 isnot fully covered. The outlets 92 a of the pressure flow-restrictors 92,which introduce the air to feed the air-cushion 95, and the vacuumoutlets 94 a of the vacuum flow-restrictors 94 through which theout-coming air is sucked from the air-cushion 95, are distributed at theactive-surface 91 in an alternating format. The of the outlets 92 a, 94a are not necessarily equal nor must have a round shape. Each of theinlets of the pressure flow-restrictors 92 is fluidically connected to abottom-side pressure reservoir 96, that is fluidically connected to anair-pump 96 a to provide pressurized air, and each of the inlets of thevacuum flow-restrictors 94 is fluidically connected to a bottom-sidevacuum reservoir 97, that is fluidically connected to a vacuum-pump 97 ato provide “active” evacuation by vacuum suction. Alternatively, each ofthe inlets of the pressure flow-restrictors 92 and the inlets of thevacuum flow-restrictors 94 is fluidically connected to a bottom-sideintegrated double-manifold to be described hereafter (see FIG. 15 b),that is fluidically connected to an air-pump 96 a and vacuum pump 97 a.

In accordance with another preferred embodiment of the present inventionreference is now made to FIG. 9 c, where the flat active-surface 91 ofthe PV-type non-contact platform 90 c is divided to several segments,where a division to two segments 99 in perpendicular to the object 500direction of motion 501 is shown in FIG. 9 c. The active-surface 91,equipped with both a plurality of pressure flow-restrictors 92 andvacuum flow-restrictors 94, preferably two different SASO nozzles,having an outlets 92 a, 94 a distributed at the active-surface 91 in analternating format. The active-surface 91 can be divided also inparallel to the direction of motion or in a two-dimensional manner. Inparticular, such open spaces can optionally be used for assisting theprocess that takes place above the object through these open spaces, andit also allows to perform a dual-sided processing of the object. It canalso be used for handling and conveying tools, and to position sensorsfor motion or process control. Other relevant details where discussedwith respect to FIG. 9 a or 9 b. The active surface may be provided withone or more through-openings for the purpose of assisting the processingof the object and for handling operations on the object.

In accordance with another preferred embodiment of the present inventionreference is now made to FIG. 9 d, illustrating the PV-type non-contactplatform 90 d having a flat active-surface 91 that equipped with both aplurality of pressure flow-restrictors 92 and vacuum flow-restrictors94, (preferably two different SASO nozzles),

-   -   having outlets 92 a, 94 a distributed at the active-surface 91        in an alternating lines format (and not in a chess-table        format), to provide enhanced flattening performances in an        effective direction that is not perpendicular to these lines.        For the same matters, it is an option to replace a limited        number of vacuum flow-restrictor 94 with vacuum conduits with no        flow restrictors.

In accordance with another preferred embodiment of the present inventionreference is now made to FIG. 9 e, illustrating the upper-grippingPV-type non-contact platform 90 e having a downwards-facing flatactive-surface 91 that is equipped with both a plurality of pressureflow-restrictors 92 and vacuum flow-restrictors 94, (preferably twodifferent types of SASO nozzles), having outlets 92 a, 94 a distributedon the active-surface 91. In this case the object 500 is suspended atrest or conveyed in direction 501 with no-contact while it is grippedwithout contact from its upper side.

The scope of using the PV-type platforms is wide. In accordance withsome preferred embodiments of the present invention, without derogatingthe generality, reference is now made to FIGS. 9 f-h, where the PV-typeplatform is a carriage having an active-surface that can travel over apassive flat surface. The first example is illustrated in FIG. 9 f,where a carriage 510 having a flat lower active-surface (not seen on thefigures). The carriage is traveling over a wide flat table 520 where amotion in all directions is available. The carriage may have its ownpressure and vacuum source or alternatively, it may fluidicallyconnected to pressure and vacuum sources (not shown in the figures forbrevity) though flexible pipes 540. This configuration can be appliedalso upside down where the carriage 510 is suspended under the flattable 520, which is located over it, (see FIG. 9 h). Furthermore, thisconfiguration is also relevant in case where the carriage 510 is thepassive element and the flat table 520 is the active one. It is anoption to use also PA-type platform (but not in the upper grippingoption), in such configuration, especially when heavy loads areinvolved.

FIG. 9 g illustrates a configuration for linear motion where a carriage511 has a bottom flat active-surface (not seen on the figures). Thecarriage is traveling over an elongated flat pathway 521, and may belaterally limited from both sides by two limiting rails 531 (which mayoptionally be two opposing vertical non-contact surfaces to provideaccurate and stable frictionless motion). The direction of motion isdenoted by the arrow. The carriage optionally has its own pressure andvacuum source, but, alternatively, it may be fluidically connected topressure and vacuum sources though flexible pipes 541. Thisconfiguration is also relevant in case where the carriage 511 is thepassive element and the flat table 521 is the active one. It is also anoption to use the PA-type platform in such configuration, especiallywhen heavy loads are involved.

FIG. 9 h illustrates an up-side-down configuration with respect to FIG.9 g, to be used for linear motion where a carriage 512 has an upper flatactive-surface (not seen on the figures). The carriage is travelingbelow an elongated flat pathway 522, suspended by the PV-air-cushionfrom the upper side of it. The object may be laterally limited from bothsides by two limiting rails 532 (which may optionally be two opposingvertical non-contact surfaces to provide accurate and stablefrictionless motion). The direction of motion is denoted by the arrow.The carriage optionally has its own pressure and vacuum source, but,alternatively, it may be fluidically connected to pressure and vacuumsources though flexible pipes 542. Again, this configuration is alsorelevant in case where the carriage 512 is the passive element and theflat table 522 is the active one.

The active-surface of the PV-type non-contact platform in accordancewith the present invention is preferably planar, suited for manysupporting and conveying purposes, but it may also be cylindrical,curved or tortuous, according to the design requirements and the natureof the supported objects that are to be conveyed on it, and it may alsodepend on the processing performed above it. A Process may take placealso at outer zones that are close to the edges of the active-area. Ithas to be emphasized that the active-surface of the PV-Type is notalways rectangular and it may be of any shape. In particular it isconvenient to use a round PV-type platform for supporting a round waferthat may be held at rest or moved in a spinning motion. Although it isconvenient to use a chess-table format for allocating the outlets of thebasic cell, the two lateral dimensions of the basic cell (see FIG. 4 a)may be equal or not. In particular, it is favorable to apply fineresolution at a limited “process zone” to enhance performance at thearea where the process is executed and, (for different reasons) toprovide fine resolution close to the edges of active-surfaces, to limitedge-effects.

In accordance with a preferred embodiment of the present inventionreference is now made to FIG. 10 a, illustrating a single flatactive-surface 101 a of the PP-type non-contact platform 100 d havingdual-side configuration (see FIG. 10 d). The active-surface 101 a isequipped with a plurality of pressure flow-restrictors 102, aimed atproviding FRS characteristics to platform 100 d and to secure thepressure level when the opposing active-surfaces are not fully covered,and a plurality of evacuation vents 103. The arrangement used for thisactive-surface follows the 8:1 ratio of a convenient basic-cell given inFIG. 6 a. The air-cushion 105 a is established between one of thesurfaces of the object 500 and the facing active-surface 101 a when theobject 500, that may be larger equal or much smaller than theactive-surface 101 a, is in parallel placed in a close vicinity to theactive-surface 101 a (at a predetermined gap ε_(n)), in between thetwo-opposing active-surfaces of the dual-side platform 100 d. The objectmay optionally be held at rest or conveyed in a direction defined byarrow 501. The outlets 102 a of the pressure flow-restrictors 102, whichintroduce pressurized air to the air-cushion 105 a, and the outlets 103a of the evacuation vents 103 through which the air is evacuated fromthe air-cushion 105 a, are distributed over the active-surface 101 a atthe above mentioned basic-cell format (to provide uniform gripping andlocal balance). The diameters of the outlets 102 a, 103 a are notnecessarily equal nor must have a round shape. Each of the inlets of thepressure flow-restrictors 102 is fluidically connected to a pressurereservoir 106, that is fluidically connected to an air-pump 106 a toprovide pressurized air. Alternatively, each inlet of theflow-restrictors 102 is connected to a single-manifold integrated in thesupport surface (see FIG. 15 a), which is connected to an air-pump 106a. In case of using vacuum-preloading, the vents 103 may connect to areservoir, which is connected to a vacuum pump (not seen in the figure).

In accordance with a preferred embodiment of the present invention it isan option to divide the active surface of the PP-type non-contactdual-sided platform 100 e configuration (see FIG. 10 e), into severalsegments (a division into two segment 109 is shown in FIG. 10 b) Thisconfiguration is considered to be the most practical PP-type platform.The figure illustrates a single flat active-surface 101 b of the PP-typenon-contact platform 100 e having dual-sided configuration. Theactive-surface 101 a is provided with a plurality of pressureflow-restrictors 102 for providing FRS characteristics of the platform100 e and to secure the pressure level when the opposing active-surfacesare not fully covered, and a plurality of evacuation vents 103. Thearrangement used for this active-surface follows the 8:1 ratio of aconvenient basic-cell given in FIG. 6 a. The air-cushion 105 aestablished between the one of the surfaces of the object 500 and thefacing active-surface 101 a when the object 500, which may be larger,equal or much smaller than the active-surface 101 a, is in parallelplaced in a close vicinity to the active-surface 101 a (at apredetermined gap ε_(n)), in between the two-opposing active-surfaces ofthe dual-side platform 100 e. The object may optionally be held at restor conveyed in a direction defined by the arrow 501. The two segments109 of the active-surface 101 a are divided in perpendicular to thedirection of motion 501 and a space 109 a is opened between them throughwhich air may also be evacuated. In general, the active-surface 101 acan be divided also in parallel to the direction of motion or in atwo-dimensional manner.

In accordance with a preferred embodiment of the present invention it isan option to provide grooves on the active surface 101 a of thedual-side PP-type platform such as platform 100 d (see FIG. 10 d), asillustrated in FIG. 10 c. Grooves 108 are provided in parallel to thedirection of motion 501 but they may be also aligned at any practicaldirection and dimension. Grooves can also be provided in atwo-directional manner. The grooves may actually includeevacuation-holes 108 c and may also have an end 108 d before reachingthe active-surface 101 a edges to direct the evacuated flow to the otherside. The grooves may evacuate part of the out-coming flow asillustrated in the figure or perform most of the evacuation task,together with the edges of the active-area. In addition, such groovescan be optionally used for assisting the process that may take placeabove the object. They can also be used for handling and conveyingtools, and for positioning sensors for motion or process control.

The active-surface of the PP-type non-contact platform in accordancewith the present invention is preferably planar, suited for manysupporting and conveying purposes, but may also be cylindrical or of anyother practical shape, according to the desig requirements and thenature of objects supported or conveyed on it, and it may also depend onthe nature of anticipated processing performed in the space between twosegments of the PP-type platform, having two opposing active surfaces.In particular it is convenient to use a round PP-type platform tosupport a round wafer that may be holds in rest or being moved in aspinning motion. Although it is convenient to use the basic-cell format(see FIG. 2 a), the two lateral dimension may not necessarily be equal.It is favorable to apply fine resolution close to the edges ofactive-surfaces.

In accordance with a preferred embodiment of the present invention,reference is made to FIG. 10 d, illustrating a dual-sided PP-typenon-contact platform 100 d, having two opposing substantially identicalactive-surfaces, an upper active-surface 400 a, similar to theactive-surface 101 a illustrated in FIG. 10 a, and a substantiallyidentical lower active-surface 400 b. Alternatively, the active-surface101 a with surface grooves illustrated in FIG. 10 c may also be used.The two opposing active-surfaces 400 a, 400 b of the platform 100 d arein parallel aligned at a narrow distance in between them. The object 500is gripped without contact by the aerodynamic forces exerted on it bythe dual-sided platform 100 e from both its sides. The object 500, whichmay be larger, equal or much smaller than the active-surfaces 101 a, isin parallel placed in a close vicinity to the active-surfaces 400 a, 400b of the dual-side PP-type platform 100 d (at a similar predeterminedair-cushion gaps). The object 500 may optionally be held at rest orconveyed in a direction defined by the arrow 501. The gaps of the twoopposing air cushions, ε₁ of the upper air-cushion that is establishedbetween the upper-side of the object 500 and the upper active-surface400 a and ε₂ of the lower air-cushion that is established between thelower-side of the object 500 and the lower active-surface 400 b can beidentical or different. Different gaps can be situated by regulating thepressure of one of the active-surfaces, to adjust the levitationclearance with respect to any spatial requirements. The object 500 isgripped without contact in between the opposing active-surfaces 400 a,400 b of the dual-side PP-type platform 100 d, having a predetermineddistance that is equal to the object width “w” plus ε₁ plus ε₂. If theobjects may have different width, a “panel-width regulating mechanism”may be added to the dual-side PP-type platform 100 d (not seen it thefigure) in order to adjust the distance between the opposing surfaces.The pressure is individually supplied to the upper pressure reservoir106, which is fluidically connected to an air-pump 106 a, and to thelower pressure reservoir 107, that is fluidically connected to anair-pump 107 a. Alternatively, the two pressure reservoirs can bereplaced by a single-manifold integrated in the surface (see FIG. 15 a),Alternatively, one air-pump is used to supply pressurized air to boththe upper and the lower active-surfaces.

In accordance with another preferred embodiment of the presentinvention, the active-surfaces are divided into several segments and adual-side PP-type non-contact platform 100 e with two segments, 109-l,109-r as illustrated in FIG. 10 e. The dual-side PP-type non-contactplatform 100 e has two opposing identical active-surfaces, a dividedupper active-surface 400 a, identical to the divided active-surface 101b illustrated in FIG. 10 b, and an identical lower active-surface 400 b.The two opposing active-surfaces 400 a, 400 b of the non-contact PP-typeplatform 100 e are in parallel aligned at a narrow distance in betweenthem. The object 500, that may be larger, equal or much smaller than theactive-surfaces 101 a, is in parallel placed in a close vicinity to theactive-surfaces 400 a, 400 b of the dual-side platform 100 a (at asimilar predetermined air-cushion gaps). The object 500 is grippedwithout contact by the dual-sided platform 100 e from its both-sides.The object 500 may be held at rest or conveyed in a direction defined bythe arrow 501.

In accordance with another preferred embodiment of the presentinvention, reference is made to FIG. 10 f, illustrating the dual-sidePP-type non-contact platform 100 d, positioned in a verticalorientation. In this vertical case, the foot print of the platform maybe small, in-particular when wide-format objects such as FPD areinvolved. Object 500 may be vertically held at rest or conveyed in adirection defined by the arrow 501. It must be mentioned that verticalorientation provides the option to convey, and to perform any processwhere vertical orientation has any kind of advantages.

The performances of the dual-side PP-type non-contact platform can bedetermined by specifying a variety of mechanical and aeromechanicalmeans, including, (1) the dimensions of the platform with respect to theobject dimensions. It includes allocation of optional relaxation areasto decay the outside disturbances and vibrations (2) theflow-restrictors characteristics (and with respect to the preferredflow-restrictor, by specifying the geometrical parameters of the SASOnozzle configuration and physical dimensions), (3) the air-cushion gapsε_(n), (4) the PP-type air-cushion basic-cell dimensions and details,(5) the operational pressure conditions, including optional means ofregulation and control, and considering the possibility to apply localpressure regulation by dividing the active-surfaces, or one of them, orpart of one on them to several individually regulated sectors to enhanceflatness-accuracy. For the PP-type dual-side platform, one-dimensionalsectors distribution is applicable at the edges areas that are close tothe laterally wide and short space where processing may take place, asshown in the divided configuration, see FIG. 10 d, (6) using of vacuumpreloading to enhance AD-stiffness. From the application point of view,the aeromechanic design considerations preferably include the (7)flatness accuracy, flattening capabilities and other performancesspecifications (8) the character of the object (materials aspects,non-flatness imperfections, width bodyweight and dimensions), (9) thedetails of the motion involved, and (10) details of the processinvolved, including dimensionality and forces that may be imposed by theprocess.

The dual-side configuration of the pressure-preloaded PP-typenon-contact platform provides high performance in terms of AD-stiffness,flattening capabilities and flatness-accuracy. It is mainly applied forproviding accurate motion and flatness and parallel accuracies withrespect to a processing machine, in cases of handling wide format planerobjects. When non-contact gripping is applied by the dual side PP-typeplatform the following advantages are directly provided: (1) There is nocontamination signature by contact. (2) No ESD (electrostatic discharge)problems or any other connecting or disconnecting problems (3)out-coming disturbances and vibrations are decayed. The PP-type platformeffectively provides high performances in cases where the object isbowed or deformed in terms of up to a few millimeters with respect tothe object characteristics and dimensions, It particular, it can flattenflat object having a width of few millimeters and more, with respect tothe object characteristics and dimensions.

The opposing air-cushions of the dual-side PP-type platform may developlarge counter forces on the object and accordingly on the structure ofthis dual-side PP-type platform that support the two opposingactive-surfaces. Therefore, the structure must be of a very strong toavoid deformations that may affect the accuracy. The loads that involvedare created when the object is placed in between the two opposingactive-surfaces of the PP-type platform, but due to the evacuation ventsor grooves or both, when an object with a width that is significantlylarger than ε_(n) travels, loading occurs locally and temporarily onlyat the “active areas”. If there is no object inside, the loads aresignificantly reduces, and practically may vanish.

With respect to mechanical means that may optionally be applied to awell-functioning dual-side PP-type platform, “panel-width adjustmentmechanism” may be desired. In addition, such a mechanism can be a manualmechanism or fully automatic. Such a platform must include mechanicaladjusting means to adjust the position and the orientation in term offlatness and parallelism with respect to the process machine or to anyrequired reference. Shock observers are preferable to isolate anyout-coming disturbances and vibrations.

It also preferable to add up-wise inlet section to the dual-side PP-typeto direct the object leading edge to be smoothly inserted, preferablywithout contact and friction, in between the two opposingactive-surfaces. Such an inlet may involve mechanical means such asroller and low friction materials or aeromechanic guiding means such asactive-surfaces of the inlet and air-jets that may apply non-contactflattening forces by impingement to provide essentially in-motioninsertion of the object. Alternatively, essentially motionless insertionprocess may applied where the inlet can be a unit with twoactive-surfaces where one of them is removed as needed for the insertionperiod and later it is returned towards the resting opposingactive-surface that optionally may temporary is been switched to vacuum,in order to provide additional means of flattening (in-contact). Afterinsertion, the in-motion active-surface closing back the gap and flattenthe object during its motion. Finally the gap is adjusted to theoperational gap (the object width+twice ε_(n)). If vacuum switching wasused, as mentioned above, switching back to operational pressure wouldterminate the insertion period and the object or its leading edge zonewill be gripped and flattened without contact, ready for the followingoperations.

To avoid possible critical damage (both to the object and the platform),when trying to insert by mistake a flat object that is wider thanintended, it is preferable to apply friendly barriers such as rollers orlinear leaf-spring with a sensor capable of sending control alarmsignal, thus stopping the process and avoiding such insertion failure.For this reason and with respect to the temporal nature of the loadingduring cycles of operations, it is preferable to connect the opposingactive-surfaces of the PP-type platform via pre-loaded mechanical springwhere as long as the force are below a predetermined limit, the platformact as usual but when, for any reason (width is not uniform, wider thanexpected or too-high operational pressure, to mention just a few) forcedreache the allowed limit, the active-surfaces, or one of it is slightlypushed away in a self-adaptive manner (preferable to the counterdirection with respect to the process). It provides a self-adaptivemechanism that limits the AD-forces and the forces acting on thestructure to a predetermined value. A mechanical limiter for thismechanism may also be supply to allowed only small movements withrespect to the air-cushion gap as it may be a non-parallel mechanism,unless it is designed for only one-directional translation movements. Asignal to the main control unit may also be involved.

It has to be emphasized with respect to the divided-active surfaces thatidentical opposing divisions must be made for the upper and the loweractive-areas, otherwise it will not function properly. A locally nonbalanced and not identical setup creates an asymmetric situation whichcauses strong local loading from one side and strong mechanical contactthat may end with high friction forces if the object is in motion.Accordingly, the platform will malfunction and all required performance,in particular flatness-accuracy, will be severely damaged.

It is also important to emphasize that with respect to a preferreddual-side platform embodiment of the present invention, a dual-sidenon-contact platform can also be created on the basis of the PV-typeactive-surface as a replacement to PV-type active-surface. In such acase, the dual side PV-type platform has the essential advantages of thepressure-preloading mechanism, and additionally, vacuum-preloadingmechanism. Although it may provide less AD-stiffness than the PP-type,due to the local “effective area” consequences, and accordingly lessflattening performance, the dual-side PV-type platform is “passive” withrespect to the loads imposed on the structure and, in fact, the outwardforces practically vanish when it is operated at the nominal gaps(ε_(n)). Nevertheless, in an off-set position, large forces may load thestructure but they are much smaller than those developed in the PP-typeplatform. Although the dual side PV-type platform is a complicatedplatform with respect to the PP-type dual-side platform and additionalvacuum source must be incorporated, It has the additional followingadvantages (1) It is allowed making of the upper and the loweractive-surfaces slightly different without causing total malfunctioning,but it must be carefully designed. (2) upper side gripping can beapplied during the insertion period. (3) switching to vacuum table isinherently available. It is also allowed to make a combination and touse PP-type active surface from one-side and PV-type active surface fromthe other side to create, for any reason, a mixed dual-side non-contactplatform without causing total malfunctioning, but, again, it must becarefully designed.

In accordance with a preferred embodiment of the present invention,reference is made to FIG. 11 a, illustrating another dual-sidednon-contact platform 110 a, each opposing surface being of the PV-type.

In accordance with a preferred embodiment of the present invention,reference is made to FIG. 11 b, illustrating the dual-side PM-typenon-contact platform 110 b. where the upper surface is an active surface111 such as shown in FIGS. 10 a-c and the lower surface 112 is a passiveflat surface capable of absorbing the AD imposed forces. When thePM-type platform is operated, forces are applied without contact to holddown the object 500, holding it pressed against the lower passivesurface. Accordingly the object 500 is “flattened against a wall” andfriction forces that may be useful to provide non-slippery motion aredeveloped with respect to the upper air-cushion operational pressure. Infact a PP-type platform can immediately change its functionality to aPM-type platform by just switching of the pressure of the lower surface.The surface 112 can also be created with evacuation vents 113.Alternatively, the surface 112 is a vacuum table (not seen in thefigure). Alternatively, the upper active-surface 111 may be divided intosegments without respect to the lower passive surface 112. Thelower-surface may be held at rest, or alternatively, the lower surfaceis used as a traveling table carrying the object as it travels. Withoutderogating the generality, the PM-type can be essentially of a flat or acylindrical structure, and of a rectangular or around shape. In additionthere is no restriction to apply such a platform upside down andirrespectfull of gravity.

In accordance with a preferred embodiment of the present invention,reference is made to FIG. 12 showing different practical applicationsfor the PM-type platform. Case 120 a illustrates a PM-type platformwhere the unit 121 a has a lower active-surface and induces pressureforces on object 500 from a distance ε_(n) thus the object is flattenedagainst the passive-surface of unit 122 a, where both units are at rest.Both 121 a and 122 b are of substantially identical dimensions and theobject is of different dimensions. Alternatively, the lower unit 122 ais a vacuum table. Case 120 b illustrates a PM-type platform where unit121 b has a lower active-surface which induces pressure forces on object500, thus flattening it against the surface of the passive-unit 122 b.The upper active-unit 121 b is smaller than unit 122 b and it travels indirection 501. Both unit 122 b and the object 500 are at rest. Case 120c illustrates 6 active segments 121 c that press the object 500 againstthe passive-unit 122 c which is traveling with the object 500 indirection 501. Alternatively, the traveling unit 122 c is a vacuumtable. Case 120 d is similar to case 120 a but the opposing surfaces arecylindrically shaped, thus the object 500 is bowed against the lowerunit 122 d. Case 121 e illustrates a round shaped unit where the upperunit 121 e is capable of rotating. FIG. 120 f illustrates a drivingcylinder 122 f that revolves in direction 501 and provides tensilemotion to a flex media 500 where the friction forces is determined bythe pressure that is induced by the active-unit 121 f.

In accordance with a preferred embodiment of the present invention,attention is made to a specific structure of a typical active-surfacewith integral manifolds as shown in FIGS. 13-15. FIG. 13 illustrates alayered assembly of the active-surface having a top plate 130 thatprovides the top structural rigidity of active-surface 131. theintermediate plate 132 is the nozzles-plate and the lower plate 133 isthe cover plate. The outer elongated manifold 134 with pressureconnector 135 and optimally also with vacuum connector 136 provide theoperational conditions in a one directional manner. Optional designdetails of the layers are shown, for example, in FIGS. 14 a, 14 b, 15 a,15 b. FIG. 14 a illustrates a nozzles-plate in cases where only pressureflow restrictors such as SASO nozzles are provided. Such a nozzles-platecan be for example, manufactured using Lasers (Yag and Co₂), or bypunching or molding. It is possible to produce individualflow-restrictors, but it is convenient and cost-effective to manufacturesuch nozzles-plate, from assembly considerations. FIG. 14 a presents athin plate (typically 0,1-4 mm thickness), having a plurality offlow-restrictors 152 having outlets 151 such as SASO nozzles and aplurality of through-holes 151 provided as the evacuation vents (eitherfor free evacuation of air or coupled to a vacuum reservoir for activesuction of the air, but without flow restrictors). It is an option tocreate a plurality of internal supply ducts 144 aligned in parallel (nota must), where each pair of flow-restrictors has shared inlets as shownin the right side. Alternatively each flow-restrictors is individuallyconnected to the internal supply ducts 144 a as shown it the left side.The air is supplied to the internal ducts by cross-layer passages 146.FIG. 14 b illustrates a nozzles-plate in cases where also vacuumflow-restrictors 153 have outlets 151 (from which the air is sucked bythe vacuum), such as SASO nozzles. The pressure flow-restrictors 152have a significantly larger AD-resistance with respect to the vacuumflow-restrictors 153. Each of the pressure flow-restrictors 152 isconnected to the pressure internal ducts 144 and each of the vacuumflow-restrictors 152 is connected to a second set of vacuum internalpressure ducts 145. The pressurized air to the pressure internal ductsis supplied by cross-layer passages 146, and the vacuum suction to thevacuum internal ducts is supplied by cross-layer passages 147. Thisfigure presents one option of creating internal supply ducts inside thenozzles plates, but it is an option to create also ducts at the topplate or the bottom plate, or any practical combination.

FIG. 15 a illustrates an integral single-manifold with respect to thenozzles plate shown in FIG. 14A. The top part of the figure present themain pressure manifold 155 with a pressure connector 159 and internalchannel 157 that is substantially orthogonal to the internal pressureducts 144, thus it provides pressurized air to each of the internalpressure ducts 144 through the cross-layer passages 146. Accordingly,channel 157 is much wider than the internal ducts typical width, todeliver a predetermined MFR without pressure losses. Cross section AA(option 1) illustrates a case where the internal pressure ducts 144 arecreated at the lower surface of the cover plate 143 and cross section AA(option 2) illustrates a case where the internal pressure ducts 144 arecreated at the upper surface of the top plate 141 having theactive-surface 140. Cross section BB shows the evacuation vents 149having outlets 151, crossing the three layers assembly.

FIG. 15 b illustrates an integral double-manifold with respect to thenozzles plate shown in FIG. 14B. The top part of the figure present themain pressure manifold 155 with a pressure connector 159 and internalchannel 157 that is substantially orthogonal to the internal pressureducts 144, thus it provides pressurized air to each of the internalpressure ducts 144 through the cross-layer passages 146. Accordingly,channel 157 is much wider than the internal pressure ducts' typicalwidth, to deliver MFR without pressure losses. In addition the integraldouble-manifold includes a main vacuum manifold 156 with a vacuumconnector 160 and internal channel 158 that is substantially orthogonalto the internal vacuum ducts 145, thus it provides vacuum to each of theinternal vacuum ducts 144 through the cross-layer passages 147.Accordingly, the channel 158 is much wider than the internal vacuumducts' typical width, in order to deliver MFR without vacuum losses.Cross section M illustrates schematically a cross-section of thepressure flow-restrictors 152, and cross section BB illustratesschematically a cut of the vacuum flow-restrictors 153.

Without derogating the generality, When a non-contact platform isapplied to support the object with no contact there are two essentialoptions. Firstly, the supported object may be made to be supported atrest. The object position can be fixed in place with respect to theplatform by using of several side pins or cylinders or circumferentialguiding plates. Alternatively It can be fixed in place by several vacuumpads that hold the object's lower or upper or side surfaces orcircumferential elongated vacuum gripping. Alternatively it may be heldmechanically by edge grippers. All those examples are aimed atpreventing lateral motion and movements. Some of the means to hold theobject at rest may be integrated in the non-contact platform.

Secondly, when motion is desired, the supported object travels withoutcontact over the support-surface of the platform and may be driven bypushing pins or pushing guiding plate. Alternatively the object may bedriven by horizontal rollers or cylinders, or vertical drive cylindersthat touch the object edges, or belts, where friction may be enhanced bynon contact induced forces (implementing a PM unit). Alternatively theobject is driven by a one or two side gripper bars that hold the objectside edges, by several mechanical dampers or by several vacuum pads atone or two of the object side edges. Alternatively the object may bedriven by a gripper bar that holds the leading or the trailing edge ofthe object by mechanical dampers or vacuum pads. When the no-contactplatform is a vertically oriented the object may tilt by a driven uppergripper bar or by bottom side rollers or belt. Alternatively the objectis moved by a lower or upper drive mechanism that has vacuum pads toclamp internal areas of the lower or the upper surfaces of the object.In case of round non-contact platforms, the object may be rotated by adriving cylinder that touches the edge of a round object or clamped by aspinning circumferential open rig that has internal dampers or vacuumpads, thus relative motion between the object and the clamping unit isavoided. When non-contact platform supports an object, lateral androtational movements can be easily performed by a robotic hand tomanipulate the positing of the object as required. For example, it isconvenient to use non-contact aligning and position-registration ofwafers and FPDs and to provide non-contact support at accurate linear orrotational motion when a process on wafers or FPDs takes place, wherehorizontal positioning is governed by the drive unit and the verticalposition is determined by the air-cushion that may be regulated by ADmeans. It is also an option to provide pure aerodynamic friction forcesto drive the object, and one way is to use directing jets or wall-jets.Motion, of course, must be controlled both to provide the required speedand an accurate positioning.

Basic non-contact support systems of the present invention are presentedin FIGS. 16-18. With respect to a preferred embodiment of the presentinvention, FIG. 16 illustrates a typical non-contact conveying systemhaving a long PA-type (may alternatively be PV-type) active-surface 201with pressure supply piping 201 a. the object 500 is driven in direction501 by a linear drive system having a straight pathway with twotraveling carriage 211 that support a side gripper bar 212 withmechanical gripper fingers 213 that grip the object 500 side edge thatis placed outwardly (typically up to 2 cm) from the active-surfaces. Theleft-side of the system is a loading/unloading area 203 built of 5non-contact PA-type segments 233 (PV-type may also be used). Thesegments 233 connect to the pressure supply piping 203 a. In between thesegment 233 there is a lifting and landing mechanism having a pluralitypines 215. The pins 215 may also be of non-contact pin where air-cushionis generated at each of the pines top surface (thus lateral movementmust be provided by additional means such as peripheral guiding plates)or provided with top vacuum pads. Such a system is provided with acontrol unit 240 and various types of sensors, where for example, sensor241 measured the speed of motion of the object 500. The control unit mayalso communicate with other machines.

With respect to another preferred embodiment of the present invention,FIG. 17 illustrates a typical one-sided high-performance system. Thissystem provides high performance with respect to flatness accuracy andconveys the object 500 without vibrations. It includes the loading andunloading conveying zone 201, 203 that can be a conventional (likerollers or a belt conveyer) or of non-contact nature. With respect tothe present invention, a PA-type non-contact platform is applied but itcan be also the PV-type platform. In addition, a new central PV-typeactive-surface is provides 203 having main-manifold 204 and pipe linesfor supplying pressure 204 a vacuum 204 b. If aeromechanic regulation isto be used, 204 is equipped with separately controlled pressure orvacuum sub-manifold sectors 204 c, in order to adjust locally thelevitation gap along the process zone. The PV-type unit 202 consists ofa central process-zone 200 and relaxation zones 200 a (typically ofabout 5-15 lengths of a basic cell).to decay spatial disturbances andvibrations coming from outer zones, When accurate lateral positioning isrequired, the linear drive-system must be accurate, optionally by usingan air-bearing system. Optionally, the side-gripper-bar 212 is connectedto the drive system (210,211) mechanically but it provides freedom inthe vertical direction and the side-gripper-bar is supported withoutcontact to the upper elongated active-surface 212 a. It provides also anoption to align the vertical level of the griper 212 with the object 500by AD-means (by regulating the pressure). The process in this case isperformed at the processing zone above the upper surface of object 500but it is an option also to divide the central accurate zone into twosegment 220 as shown in the left side, thus at option to assist theprocess from the lower side or to perform a dual-sided processing isavailable though the space 220 a that is opened between the twosegments. Other alternatives are: (1) to use a two side gripping bars todrive the object 500 from both sides, to eliminate dynamic moments (2)to use leading edge gripper-bar 250 shown on the lower left side that isfloating on the same air-cushion that floats the object 500, thus itprovides natural horizontal alignment between the gripper and theobject.

With respect to another preferred embodiment of the present invention,FIG. 18 illustrates a typical dual-side high-performance PP-type orPV-type system (PV-type is shown in the figure), having a dual-sidedcentral accurate section 200 that provides high flattening performanceand flatness-accuracy, and loading and unloading outer conveying zones201, 202 that can be of conventional or of non-contact nature. Withrespect to the present invention, a PA-type non-contact platform is usedbut it can be also a PV-type platform. The dual sided non-contact systemshares many details with the previously mentioned systems. The dual sidePP-type or PV-type platform opposing active-surface 200 a, 200 b and theouter conveying zones are divided into three identical segments 212, andthe drive system is implemented through the two spaces that aresymmetrically created between the segments 212. The object 500 that isclamped without contact between the opposing active-surface of 200 a,200 b is driven in direction 501 pulled from the object leading edge bya drive system 213 that has two arms traveling in the space between thesegments 212 and clamping by vacuum pads or mechanical griper 213 thesurface that is close to the leading edge of object 500. As large forcesmay develop, a rigid supporting structure is required as indicated bythe heavy bar 230. This bar is part of a panel with compensationmechanism for compensating by way of adjusting the gap between twoopposing active surfaces, when operating with different object widths.It this case the process can be taken place at the lateral central spacebetween the two segments of the accurate dual-side platform. The processcan be performed above the surface or, alternatively, a dual sideprocess can take place. Aerodynamic regulation of the flatness accuracythat is similar the system described in FIG. 21 can also be implementedin the non-contact dual side platform. Springs 230 a are optionallyprovided to act as adjust the gap between the two substantially oppositesupport surfaces in a parallel and self-adaptive manner, and limit theforces induced on the two substantially opposite support surfaces tobelow a predetermined threshold.

Although only rectangular systems where disclosed, similar platforms canbe created in a cylindrical coordinates where spinning motion isinvolved.

It should be clear that the description of the embodiments and attachedFigures set forth in this specification serves only for a betterunderstanding of the invention, without limiting its scope.

It should also be clear that a person skilled in the art, after readingthe present specification could make adjustments or amendments to theattached Figures and above described embodiments that would still becovered by the present invention. Furthermore, details and featuresdescribed herein with reference to the embodiments shown in the Figurescan be, an many cases, implemented interchangeably, optionally oralternatively, where applicable.

1. A non-contact support platform for supporting without contact astationary or traveling object by air-cushion induced forces, theplatform comprising: at least one of two substantially opposite supportsurfaces, each support surface comprising at least one of a plurality ofbasic cells each having at least one of a plurality of pressure outletsand at least one of a plurality of air-evacuation channels at least oneof a plurality of outlets, and one of a plurality of air-evacuationchannels, each of the pressure outlets fluidically connected through apressure flow restrictor to a high-pressure reservoir, the pressureoutlets providing pressurized air for generating pressure inducedforces, maintaining an air-cushion between the object and the supportsurface, the pressure flow restrictor characteristically exhibitingfluidic return spring behavior; each of said at least one of a pluralityof air-evacuation channels having an inlet and outlet, the inlet kept atan ambient pressure or lower, under vacuum condition, for locallydischarging mass flow, thus obtaining uniform support and local natureresponse.
 2. The platform as claimed in claim 1, wherein the pressureflow restrictor comprises a conduit, having an inlet and outlet,provided with two opposite sets of fins mounted on the inside of theconduit, each two fins of same set and a portion of the conduit internalwall between them defining a cavity and the fin of the opposite setpositioned opposite said cavity, so that when fluid flows through theconduit substantially stationary vortices are formed in the cavitiessaid vortex existing at least temporarily during the flow thus formingan aerodynamic blockage allowing a central core-flow between thevortices and the tips of the opposite set of fins and suppressing theflow in a one-dimensional manner, thus limiting mass flow rate andmaintaining a substantial pressure drop within the conduit.
 3. Theplatform as claimed in claim 1, wherein said at least one of a pluralityof air-evacuation channels includes an evacuation flow restrictor. 4.The platform as claimed in claim 3, wherein the evacuation flowrestrictor comprises a conduit, having an inlet and outlet, providedwith two opposite sets of fins mounted on the inside of the conduit,each two fins of same set and a portion of the conduit internal wallbetween them defining a cavity and the fin of the opposite setpositioned opposite said cavity, so that when fluid flows through theconduit substantially stationary vortices are formed in the cavitiessaid vortex existing at least temporarily during the flow thus formingan aerodynamic blockage allowing a central core-flow between thevortices and the tips of the opposite set of fins and suppressing theflow in a one-dimensional manner, thus limiting mass flow rate andmaintaining a substantial pressure drop within the conduit.
 5. Theplatform as claimed in claim 1, wherein the evacuation channels arefluidically connected to a vacuum reservoir.
 6. The platform as claimedin claim 5, wherein the vacuum flow restrictor has significantly loweraerodynamic resistance than the pressure flow restrictor.
 7. Theplatform as claimed in claim 6, wherein the vacuum flow restrictors aredesigned so as to lower the vacuum level to a value in the range of70%-90% of the vacuum of the vacuum reservoir.
 8. The platform asclaimed in claim 7, wherein the absolute value of pressure supply to theplatform is larger by a factor of 1.2.-3 with respect to the absolutevalue of vacuum supply to the platform.
 9. The platform as claimed inclaim 1, wherein the support surface comprises at least one of aplurality of planar surfaces.
 10. The platform as claimed in claim 9,wherein the support surface is flat.
 11. The platform as claimed inclaim 9, wherein the support surface is provided with grooves.
 12. Theplatform as claimed in claim 9, wherein the support surface iscylindrically shaped.
 13. The platform as claimed in claim 1, whereinthe support surface is substantially rectangular.
 14. The platform asclaimed in claim 1, wherein the support surface is substantiallycircular.
 15. The platform as claimed in claim 1, wherein the supportsurface is constructed from plates in a layered formation.
 16. Theplatform as claimed in claim 15, wherein at least one of the platescontains a plurality of voids constructing the flow restrictors andinter-layer passages for the air-evacuation channels and for pressure orvacuum supply.
 17. The platform as claimed in claim 15, wherein thepressure reservoir is in the form of an Integral manifold within thelayered-formation.
 18. The platform as claimed in claim 17, wherein theevacuation channels are fluidically connected to a vacuum reservoir andthe vacuum reservoir is in the form of an Integral manifold within thelayered-formation, constituting a double-manifold structure.
 19. Theplatform as claimed in claim 1, wherein said at least one of a pluralityof basic cells is provided in a repeated arrangement in order to providelocal balance.
 20. The platform as claimed in claim 19, wherein thebasic cell is provided in a one-dimensional repeated arrangement. 21.The platform as claimed in claim 19, wherein the basic cell is providedin a two-dimensional repeated arrangement.
 22. The platform as claimedin claim 1, wherein the pressure flow restrictors are designed so as toreduce the pressure supplied by the pressure reservoir to a value in therange of 30%-70% of the pressure of the pressure reservoir, to beintroduced through the pressure outlets to the air-cushion.
 23. Theplatform as claimed in claim 1, wherein at least one of a plurality ofthrough-openings is provided in the support surface, for allowing accessto the object for handling or processing.
 24. The platform as claimed inclaim 1, wherein the support surface is segmented into several segments,separated by spaces.
 25. The platform as claimed in claim 1, wherein theevacuation channels are fluidically connected to a vacuum reservoir, andwherein pressure level in the pressure reservoir or vacuum reservoir isregulated to adjust globally levitation gap of the object over thesupport surface.
 26. The platform as claimed in claim 1, wherein theevacuation channels are fluidically connected to a vacuum reservoir, andwherein pressure level in the pressure reservoir or vacuum reservoir isregulated in at least one selected separated zone of the pressurereservoir or vacuum reservoir, in order to locally adjust t levitationgap of the object over the support surface.
 27. The platform as claimedin claim 1, wherein the evacuation channels are fluidically connected toa vacuum reservoir and wherein along a line of selected separated zonesof the pressure reservoir the pressure is individually regulated, inorder to flatten the object over the support surface along that line.28. The platform as claimed in claim 27, wherein the along the lineselected separated zones parallelism is maintained with respect to anindependent reference.
 29. The platform as claimed in claim 26, whereinthe selected separated zones are located at edges of the support surfaceto suppress edge effects.
 30. The platform as claimed in claim 1,wherein resolution of basic cells at edges of the support surface ishigher with respect to inner zones of the support surface, in order tominimize degrading edge effects of the air-cushion.
 31. The platform asclaimed in claim 1, wherein the basic cell comprises at least one of aplurality of evacuation grooves, serving as an air-evacuation channel.32. The platform as claimed in claim 31, wherein the basic cellcomprises at least one of a plurality of evacuation vents, serving as anair-evacuation channel.
 33. The platform as claimed in claim 1, whereinthe basic cell comprises at least one of a plurality of evacuationvents, serving as an air-evacuation channel.
 34. The platform as claimedin claim 1, wherein pressure outlets and evacuation channels arearranged linearly, pressure outlets aligned in lines and evacuationchannels aligned in lines.
 35. The platform as claimed in claim 1,wherein said at least one of two substantially opposing support surfacesis oriented so that the object is to be supported below it.
 36. Theplatform as claimed in claim 1, wherein the platform is adapted to besupported or conveyed over the object, which is stationary.
 37. Theplatform as claimed in claim 36, wherein the object is a carriage andthe support surface is an elongated track.
 38. The platform as claimedin claim 37, wherein the track is provided with rails on opposing sidesof the track to limit the motion of the object to a predetermined pathover the track.
 39. The platform as claimed in claim 38, wherein therails comprise each a platform as claimed in claim 1, for eliminating orgreatly reducing friction forces.
 40. The platform as claimed in claim1, wherein the object is a flat track and the support surface isincorporated in a carriage.
 41. The platform as claimed in claim 40,wherein the track is provided with rails on opposing sides of the trackto limit the motion of the carriage to a predetermined path over thetrack.
 42. The platform as claimed in claim 41, wherein the railscomprise each a platform as claimed in claim
 1. 43. The platform asclaimed in claim 1, wherein the ratio between the number of pressureoutlets and evacuation channels is in the range of 3-16.
 44. Theplatform as claimed in claim 1, wherein gripping means are provided tobe coupled to the object for holding or moving the object over thesupport surface.
 45. The platform as claimed in claim 44, wherein thegripping means comprise a gripper unit, which itself is supported withno contact by a support surface such as the one claimed in claim
 1. 46.The platform as claimed in claim 45, wherein the gripping means comprisea gripper unit, which itself is supported with no contact by the supportsurface.
 47. The platform as claimed in claim 44, wherein the grippingmeans is coupled to the object and used to convey it over the supportsurface sideways.
 48. The platform as claimed in claim 47, whereingripping means is coupled to the object and used to convey it over thesupport surface in a linear motion.
 49. The platform as claimed in claim47, wherein gripping means is coupled to the object and used to conveyit over the support surface in a rotational motion.
 50. The platform asclaimed in claimed in claim 44, wherein the gripping means is coupled tothe support surface and the support surface is transportable.
 51. Theplatform as claimed in claim 1, wherein the platform is verticallyoriented.
 52. The platform as claimed in claim 1, wherein theair-evacuation channels allow air to be passively discharged intoambient atmosphere.
 53. The platform as claimed in claim 52, whereinmore flow restrictors are provided for each basic cell in order tosupport a heavier object and vice versa.
 54. The platform as claimed inclaim 52 wherein the evacuation channels are placed closer to pressureoutlets for supporting a very light object.
 55. The platform as claimedin claim 54, wherein the higher the supply pressure is provided to thepressure reservoir the smaller the risk of contact between the objectand the support surface.
 56. The platform as claimed in claim 1 designedto support an object which substantially covers the support surface,wherein the each of the air-evacuation channels is fluidically connectedto a vacuum reservoir, thus generating vacuum-induced forces on theobject, facilitating unilateral gripping of the object without contactby both the pressure induced forces and the vacuum induced forces, whichact in opposite directions, where aerodynamic stiffness of theair-cushion is augmented by vacuum-preloading.
 57. The platform asclaimed in claim 1 designed to support an object substantially issmaller than the support surface, wherein the each of the air-evacuationchannels is fluidically connected to a vacuum reservoir through a flowrestrictor, thus generating vacuum-induced forces on the object,facilitating unilateral gripping of the object without contact by boththe pressure induced forces and the vacuum induced forces, which act inopposite directions, where aerodynamic stiffness of the air-cushion isaugmented by vacuum-preloading.
 58. The platform as claimed in claim 1,wherein said at least one of two substantially opposite support surfacescomprise only one support surface, and opposite it a passive surface isprovided so that the object may be pressed against the passive surfacewithout contact by aerodynamically induced forces generated by thesupport surface.
 59. The platform as claimed in claim 58, wherein thepassive surface is adapted to be laterally moved.
 60. The platform asclaimed in claim 59, wherein the passive surface is a rotatablecylinder, that can be used as a driving unit to move the object byenhanced friction forces.
 61. The platform as claimed in claim 59,wherein the passive surface is a vacuum table.
 62. A dual-sidednon-contact support platform for supporting without contact an object byair-cushion induced forces, the platform comprising: two substantiallyopposite support surfaces, each support surface comprising at least oneof a plurality of basic cells having at least one of a plurality ofpressure outlets and at least one of a plurality of air-evacuationchannels at least one of a plurality of outlets, and one of a pluralityof air-evacuation channels, each of the pressure outlets fluidicallyconnected through a pressure flow restrictor to a high-pressurereservoir, the pressure outlets providing pressurized air for generatingpressure induced forces, maintaining an air-cushion between the objectand the support surface, the pressure flow restrictor characteristicallyexhibiting fluidic return spring behavior; each of said at least one ofa plurality of air-evacuation channels having an inlet and outlet, theinlet kept at an ambient pressure or lower, under vacuum condition, forlocally discharging mass flow, thus obtaining uniform support and localnature response.
 63. The platform as claimed in claim 62, wherein eachof the air-evacuation channels is connected to a vacuum reservoir. 64.The platform as claimed in claim 63, wherein each of the air-evacuationchannels is connected to a vacuum reservoir through a vacuum flowrestrictor, the vacuum flow restrictor characteristically exhibitingfluidic return spring behavior.
 65. The platform as claimed in claim 62,wherein the two substantially opposite support surfaces aresubstantially symmetrical.
 66. The platform as claimed in claim 62,wherein a gap between the two substantially opposite support surfaces isdetermined to be at least the width of anticipated object to besupported within plus twice the desired air-cushion gap.
 67. platform asclaimed in claim 66, wherein a preload mechanical spring is provided toadjust the gap between the two substantially opposite support surfacesin a parallel and self adaptive manner, and limit the forces induced onthe two substantially opposite support surfaces to below a predeterminedthreshold.
 68. The platform as claimed in claim 62, wherein pressuresupply or vacuum to one of the two substantially opposite supportsurfaces is different from the pressure supply or vacuum supply to thesecond of the two substantially opposite support surfaces, so that thelevitation of the object between the two substantially opposite supportsurfaces may be adjusted to any desired gap in between the surfaces. 69.A system for conveying without contact a substantially flat object, thesystem comprising: at least one of two substantially opposite supportsurfaces, each support surface comprising at least one of a plurality ofbasic cells having at least one of a plurality of pressure outlets andat least one of a plurality of air-evacuation channels at least one of aplurality of outlets, and one of a plurality of air-evacuation channels,each of the pressure outlets fluidically connected through a pressureflow restrictor to a high-pressure reservoir, the pressure outletsproviding pressurized air for generating pressure induced forces,maintaining an air-cushion between the object and the support surface,the pressure flow restrictor characteristically exhibiting fluidicreturn spring behavior; each of said at least one of a plurality ofair-evacuation channels having an inlet and outlet, the inlet kept at anambient pressure or lower, under vacuum condition, for locallydischarging mass flow, thus obtaining uniform support and local natureresponse; driving mechanism for driving the object over said at leastone of two substantially opposite support surfaces; handling means forhandling the object during loading or unloading of the object onto saidat least one of two substantially opposite support surfaces; sensingmeans for sensing properties selected from the group of propertiesincluding: position, orientation, proximity and velocity of the object;and controller for controlling the position, orientation and travelingvelocity of the object over said at least one of two substantiallyopposite support surfaces and communicate with a process line adjacentthe system.
 70. The system as claimed in claim 69, wherein loading andunloading zones are provided.
 71. The system as claimed in claim 69,comprising several one-sided types of said at least one of twosubstantially opposite support surfaces.
 72. The system as claimed inclaim 71, wherein one of the several one-sided types of said at leastone of two substantially opposite support surfaces comprises a PVsupport surface for providing flattening of the object, where at centralzone of that PV support surface a processing on the object is conducted.73. The system as claimed in claim 72, wherein the PV support surface isprovided with a relaxation zone on edges of the PV support surfacehaving a relaxation length of about 5-15 lengths of basic cells.
 74. Thesystem as claimed in claim 69, further comprising at least one of aplurality of dual-sided type of said at least one of two substantiallyopposite support surfaces.
 75. The system as claimed in claim 74, thedual-sided type of said at least one of two substantially oppositesupport surfaces comprising PP-type dual-sided support surfaces for highflattening performance.
 76. The system as claimed in claim 74, thedual-sided type of said at least one of two substantially oppositesupport surfaces comprising PV-type dual-sided support surfaces for highflattening performance.